1

By its appeal, the European External Action Service (EEAS) seeks to have set aside the judgment of the General Court of the European Union of 13 April 2018, Alba Aguilera and Others v EEAS (T‑119/17, ‘the judgment under appeal’, EU:T:2018:183), by which the General Court annulled the decision of the EEAS Director-General for Budget and Administration of 19 April 2016 (‘the decision at issue’) fixing the allowance for living conditions referred to in Article 10 of Annex X to the Staff Regulations — Financial Year 2016 [ADMIN(2016) 7], in so far as that decision reduces, as of 1 January 2016, the allowance for living conditions (‘the ALC’) paid to EU staff posted to Ethiopia from 30% to 25% of the reference amount.

2

The Staff Regulations of Officials of the European Union, in the version applicable to the dispute (‘the Staff Regulations’), state, in Article 1b(a) thereof that, save as otherwise provided in the Staff Regulations, the EEAS is, for the purposes of the Staff Regulations, to be treated as an institution of the Union.

3

Article 101a of the Staff Regulations is the sole provision of Title VIIIb of those regulations. That article provides that, without prejudice to the other provisions of the Staff Regulations, Annex X to the Staff Regulations lays down the special and exceptional provisions applicable to officials serving in a third country.

4

Article 110 of the Staff Regulations, which falls under Title IX of the Staff Regulations relating to transitional and final provisions, provides:

‘1.   The general provisions implementing these Staff Regulations shall be adopted by the appointing authority of each institution after consulting the Staff Committee and the Staff Regulations Committee.

2.   Implementing rules adopted by the Commission to give effect to these Staff Regulations, including the general implementing provisions referred to in paragraph 1, shall apply by analogy to the agencies. …

…

3.   For the purposes of the adoption of rules by agreement between the institutions, the agencies shall not be treated as institutions. …

4.   Rules giving effect to these Staff Regulations, including the general implementing provisions referred to in paragraph 1, and rules adopted by agreement between the appointing authorities of the institutions, shall be brought to the attention of the staff.

…’

5

Annex X to the Staff Regulations, headed ‘Special and exceptional provisions applicable to officials serving in a third country’, contains, in Chapter 1, which is headed ‘General provisions’, Articles 1 to 3 of that annex.

6

Article 1 of the annex provides:

‘This Annex lays down the special and exceptional provisions applicable to officials of the European Union serving in a third country.

…

General implementing provisions shall be adopted in accordance with Article 110 of the Staff Regulations.’

7

The second paragraph of Article 2 of that annex states:

‘The Appointing Authority shall make such transfers by a specific procedure referred to as the ‘mobility procedure’, for which it shall lay down detailed implementing rules, after consulting the Staff Committee.’

8

Article 3 of Annex X to the Staff Regulations provides:

‘Under the mobility procedure, an official assigned to a third country may, by decision of the Appointing Authority, be reassigned temporarily with his post to the seat of the institution or any other place of employment in the Union; … By way of derogation from the first subparagraph of Article 1, the appointing authority may decide, on the basis of general implementing provisions, that the official shall remain subject to certain provisions of this Annex for the duration of this temporary assignment, excluding Articles 5, 10 and 12 thereof.’

9

Article 5(2) of that annex provides:

‘Detailed rules for the application of paragraph 1 shall be laid down by the Appointing Authority, after consultation of the Staff Committee. …’

10

Article 10 of that annex states:

‘1.   ‘An [ALC] shall be fixed, according to the official’s place of employment, as a percentage of a reference amount. That reference amount shall comprise the total basic salary, plus the expatriation allowance, household allowance and dependent child allowance, less the compulsory deductions referred to in the Staff Regulations or in the regulations adopted to implement them.

Where an official is employed in a country in which living conditions can be deemed equivalent to those normally obtaining in the European Union, no such allowance shall be payable.

In the case of other places of employment, the [ALC] shall be fixed taking into account, inter alia, the following parameters:

The [ALC] fixed for each place of employment shall be reviewed and, where appropriate, adjusted each year by the appointing authority after the opinion of the Staff Committee has been obtained.

…

3.   Detailed provisions for the application of this Article shall be decided by the appointing authority.’

11

Article 15 of that annex provides:

‘On the conditions laid down by the appointing authority, the official shall receive an education allowance …’

12

Under Article 21 of Annex X to the Staff Regulations:

‘Where an official is obliged to change his place of residence in order to comply with Article 20 of the Staff Regulations … the institution shall, subject to the conditions laid down by the Appointing Authority and depending on the type of accommodation that can be provided for him at the place of employment, bear the cost of [certain expenses].’

13

The fourth subparagraph of Article 23 of that annex is worded as follows:

‘Detailed rules for the application of this Article shall be laid down by the appointing authority. The accommodation allowance shall not in any case exceed the costs incurred by the official.’

14

The Conditions of Employment of Other Servants of the European Union, in the version applicable to the dispute (‘the CEOS’), state, in Article 10(5), that Title VIIIb of the Staff Regulations is to apply by analogy to temporary staff serving in a third country.

15

Article 118 of the CEOS provides that Annex X to the Staff Regulations is to apply by analogy to contract staff serving in third countries, subject, in certain circumstances, to Article 21 of that annex.

16

The Decision of the High Representative of the Union for Foreign Affairs and Security Policy of 17 December 2013 on the allowance for living conditions and the supplementary premium under Article 10 of Annex X to the Staff Regulations (HR DEC(2013) 013) (‘the decision of 17 December 2013’) refers to the Staff Regulations and the CEOS, in particular Article 10 itself, and states that it was adopted after consulting the Staff Committee. According to the only recital of the decision of 17 December 2013, its objective is to adopt internal guidelines relating in particular to the ALC.

17

Article 1 of that decision states:

‘The parameters set out in Article 10(1) of Annex X to the Staff Regulations shall be assessed by the appointing authority, using, for example, information provided by reliable public or private international sources, by the Member States, or by the Union delegations and the departments of the institutions and bodies of the European Union.’

18

Under the first paragraph of Article 2 of that decision:

‘After consulting the EEAS and Commission Staff Committees, the appointing authority shall determine the percentages of the [ALC] for the different places of employment. Those percentages shall be divided into eight categories …, depending on the parameters, …’

19

Article 7 of that decision lists, by way of example, the parameters which, among others, are taken into account when the ALC is fixed, which correspond to the parameters set out in the third subparagraph of Article 10(1) of Annex X to the Staff Regulations. It also provides, in essence, that, in order to specify the methodology used, the EEAS will adopt guidelines in agreement with the Commission departments responsible, after consulting an ad hoc technical group comprising members of the administration and staff representatives of the EEAS and the Commission who are appointed by the Staff Committee of their institution.

20

Article 12 of the decision of 17 December 2013 specifies that its provisions are to apply by analogy to temporary staff and contract staff and that it enters into force on 1 January 2014.

21

The Chief Operating Officer ad interim of the EEAS adopted Decision EEAS DEC(2014) 049 of 3 December 2014 on the guidelines establishing the method for setting, inter alia, the ALC (‘the decision of 3 December 2014’), on the basis of the decision of 17 December 2013, in particular Articles 2 and 7 thereof, and on the basis of Annex X to the Staff Regulations, in particular Articles 8 and 10 thereof, after consulting the EEAS Staff Committee and the Commission Staff Committee.

22

The decision at issue refers, in particular, to the decisions of 17 December 2013 and 3 December 2014 and states that it was adopted after consulting the EEAS Staff Committee and the Central Staff Committee, Non-Union Section, of the Commission. The first recital of that decision states inter alia that ‘the review and, where appropriate, the annual adjustment of the [ALC] shall be an annual exercise covering all places of employment in order to take account of changes in circumstances’ and that that exercise ‘shall include an analysis of the living conditions prevailing in each place of employment, with a view to determining whether they are, or remain equivalent to, those customary in the Union’.

23

By that decision, the appointing authority empowered to conclude contracts of employment carried out the annual review of the ALC for 2016. Taking into account the technical group’s recommendations, it reduced, with effect from 1 January 2016, the ALC rate paid to staff posted to Ethiopia from 30% to 25%.

24

The applicants at first instance, Mr Alba Aguilera and others, are EU officials or agents, either temporary or contractual, who were serving in Ethiopia when the decision at issue was adopted. Since that decision reduced the ALC rate paid to EU staff posted to Ethiopia, each of the applicants at first instance lodged, between 13 July and 18 July 2016, a complaint against the decision at issue with the appointing authority or the authority empowered to conclude contracts (‘the AECE’), contesting the reduction, pursuant to Article 90(2) of the Staff Regulations.

25

By a single decision of 9 November 2016, those complaints were rejected.

26

By application lodged at the General Court Registry on 20 February 2017, Mr Alba Aguilera and others brought an action for (i) annulment of the decision at issue in so far as it reduces, as of 1 January 2016, the ALC paid to EU staff posted to Ethiopia from 30% to 25% of the reference amount, (ii) an order that the EEAS make a lump-sum payment, to be determined ex aequo et bono by the General Court, in respect of the non-pecuniary harm suffered, and (iii) an order that the EEAS pay the costs.

27

In support of their claims for annulment, Mr Alba Aguilera and others raised three pleas in law. The first plea alleged breach of the obligation to adopt general implementing provisions in Annex X to the Staff Regulations, the second plea alleged breach of Article 10 of Annex X to the Staff Regulations in that the method used by the EEAS, in the decision of 3 December 2014, to fix the amount of the ALC in a place of employment took account of ‘regional coherence’, and the third plea in law alleged manifest errors of assessment of the criteria referred to in Article 10 of Annex X to the Staff Regulations in fixing the ALC in question.

28

By the judgment under appeal, the General Court upheld the first plea in law raised before it, annulled the decision at issue to the extent requested, dismissed the claims for damages and ordered the EEAS to pay the costs.

29

The EEAS claims that the Court should:

30

Mr Alba Aguilera and others contend that the Court should:

31

The EEAS puts forward two grounds in support of its appeal. The first ground alleges an error of law in construing the obligation, contained in Article 1 of Annex X to the Staff Regulations, to adopt general implementing provisions in accordance with Article 110 of the Staff Regulations as being equivalent to an obligation to adopt general implementing provisions for the whole of that annex. The second ground alleges an error of law in interpreting Article 10 of Annex X as constituting a provision that is so unclear and imprecise that any application of it must be arbitrary, making it necessary to adopt general implementing provisions.

32

In that regard, it should be noted, as a preliminary observation, that, by those grounds of appeal, the EEAS refers only to the grounds of the judgment under appeal by which the General Court granted the application for partial annulment of the decision at issue, without referring to the grounds of that judgment by which the General Court dismissed the claims for damages. In those circumstances, by its appeal, the EEAS does not seek to have set aside the judgment under appeal in its entirety, but only in so far as, by that judgment, the General Court annulled the decision at issue to the extent requested and, consequently, ordered the EEAS to pay the costs.

33

The EEAS submits that the General Court erred in law in its interpretation of Article 1 of Annex X to the Staff Regulations in holding, in paragraphs 30 and 31 of the judgment under appeal, that the obligation laid down in the third subparagraph of Article 1 to adopt general implementing provisions in accordance with Article 110 of the Staff Regulations is equivalent to an obligation to adopt general implementing provisions for the whole of that annex, on the ground that Article 1 is among the general provisions of that annex.

34

The scope of the third subparagraph of Article 1 of Annex X to the Staff Regulations depends on whether or not specific procedures for applying the provisions of that annex are provided for and, if not, on whether the provisions themselves are sufficiently precise or whether they need to be accompanied and developed by general implementing provisions. According to the EEAS, the position taken by the General Court has the effect of modifying the procedures laid down by that annex for adopting certain specific implementing rules, and of those provisions of the annex which are self-contained being rendered by the courts as meaningless and incomplete, which is not necessarily the case.

35

It is clear from an examination of Annex X to the Staff Regulations that only Article 3 of that annex expressly provides that the appointing authority can adopt a decision ‘on the basis of general implementing provisions’. Article 10 of that annex uses different terminology, which indicates that the EU legislature did not intend to lay down an identical procedure. The fourth subparagraph of Article 10(1) provides that the ALC is to be subject to an annual review and, where appropriate, to an adjustment ‘by the appointing authority after the opinion of the Staff Committee has been obtained’ and Article 10(3) provides that the appointing authority is to decide ‘detailed provisions for the application’ of Article 10. It is in that context that the decisions of 17 December 2013 and 3 December 2014 were adopted, after consulting the Staff Committee in respect of the former and the EEAS Staff Committee and the Commission Staff Committee in respect of the latter.

36

An overall analysis of Annex X to the Staff Regulations shows that it provides for various types of decisions and various procedures for adopting implementing measures, namely those which constitute general implementing provisions, where consultation with the Staff Committee and the opinion of the Staff Regulations Committee are required, those which constitute detailed rules of application to be adopted by the appointing authority after consulting the Staff Committee, and those which constitute terms or conditions to be laid down by the appointing authority without the obligation to consult the Staff Committee. If the EU legislature’s intention had been to make the obligation to adopt general implementing provisions applicable to all of the provisions of Annex X to the Staff Regulations, it would have stated so expressly, adopted uniform terminology throughout the annex and would not have laid down separate, specific procedures for applying some of its provisions.

37

The contradictory consequence of the General Court’s interpretation is that the implementation of Articles 2, 5 and 10 of Annex X to the Staff Regulations would involve, first, the adoption of general implementing provisions, which require the Staff Committee to be consulted, and then the opinion of the Staff Committee being obtained again in relation to the adoption of certain specific implementing measures. The Staff Committee would therefore be asked to give its opinion twice on the same matter. That could not have been the EU legislature’s intention. Moreover, such an interpretation would deprive the other provisions of that annex, in which the EU legislature has clearly provided for mechanisms that do not involve the adoption of general implementing provisions, of any practical effect.

38

According to the EEAS, the only possible interpretation of the third subparagraph of Article 1 of Annex X to the Staff Regulations is that, where a relevant provision of Annex X requires the adoption of general implementing provisions, those provisions are to be adopted in accordance with the procedure laid down in Article 110 of the Staff Regulations.

39

In addition, the EEAS submits that the first ground of appeal does not alter the subject matter of the dispute before the General Court and does not constitute a new plea. It is therefore admissible. The scope of the obligation to adopt general implementing provisions was discussed between the parties in the context of the first plea raised by the applicants at first instance, who, in that capacity, determined the subject matter of the dispute. The EEAS adds that, in any event, even on the assumption that the first ground of appeal were regarded as new, the EEAS cannot be deprived of the right to challenge the reasoning on the basis of which the General Court held that general implementing provisions are necessary for the whole of Annex X to the Staff Regulations, given that that reasoning emerged for the first time in the judgment under appeal.

40

Mr Alba Aguilera and others submit, as their principal plea, that the first ground of appeal is inadmissible. The obligation to adopt general implementing provisions for Article 10 of Annex X to the Staff Regulations, referred to by the General Court in paragraphs 30 to 33 of the judgment under appeal, is based on settled case-law which was not challenged by the EEAS at first instance, as is apparent from paragraph 25 of the judgment under appeal and paragraph 16 of the defence lodged by the EEAS before the General Court. As is clear from paragraph 27 of the judgment under appeal, the EEAS argued only that the decisions of 17 December 2013 and 3 December 2014 constituted general implementing provisions for Article 10 of Annex X, or could at least be equated to general implementing provisions. The General Court, however, held that those decisions could not be equated to general implementing provisions because the EEAS had not obtained the opinion of the Staff Regulations Committee in accordance with Article 110 of the Staff Regulations, which the EEAS does not dispute in the present appeal. Moreover, the EEAS does not claim that, in paragraph 25 of the judgment under appeal, the General Court distorted its argument.

41

According to Mr Alba Aguilera and others, the EEAS is therefore arguing for the first time before the Court that it was obliged to adopt general implementing provisions for Article 10 of Annex X to the Staff Regulations pursuant to the third paragraph of Article 1 thereof. However, the EEAS is not permitted to alter the subject matter of the dispute, otherwise it would be bringing before the Court a wider case than that heard by the General Court. Furthermore, that is not something which was revealed for the first time in the judgment under appeal, since that obligation was laid down by the Civil Service Tribunal in the judgment of 25 September 2014, Osorio and Others v EEAS (F‑101/13, EU:F:2014:223) and confirmed in the judgment of 17 March 2016, Vanhalewyn v EEAS (T‑792/14 P, EU:T:2016:156). In addition, the fact that the EEAS had not complied with those judgments by adopting general implementing provisions before issuing a decision fixing the amount of the ALC in question was identified in the pre-litigation phase. The judgment under appeal did not, therefore, ‘reveal’ anything.

42

In any event, the first ground of appeal is unfounded. Article 1 of Annex X to the Staff Regulations falls under the chapter on general provisions and the third subparagraph of that article is worded in general terms. It follows that the EU legislature requires general implementing provisions to be adopted for the whole of that annex. The third subparagraph of Article 1 thus precludes the EEAS from reducing the amount of the ALC received by the applicants at first instance without first adopting general implementing provisions for the implementation of Article 10 of that annex, as the General Court rightly held in the judgment under appeal.

43

The argument put forward by the EEAS derived from the fact that the EU legislature has on occasion specified that the adoption of general implementing provisions is required for a specifically identified provision does not support its position. If the EU legislature had genuinely intended to limit the obligation to adopt general implementing provisions in Annex X to the Staff Regulations to certain provisions of that annex, it would have made that clear.

44

Nor can the other arguments put forward by the EEAS be upheld. First, the fact that Article 3 of Annex X to the Staff Regulations specifically provides for the adoption of general implementing provisions under that article is irrelevant, as the Civil Service Tribunal previously held in paragraphs 24 and 25 of the judgment of 25 September 2014, Osorioand Others v EEAS (F‑101/13, EU:F:2014:223). Since Article 3 of Annex X to the Staff Regulations is provided for by way of derogation from the first subparagraph of Article 1 of that annex, which refers to the provisions of the annex, the general implementing provisions referred to in Article 3 could not refer to the general implementing provisions provided for in the third subparagraph of Article 1 or, consequently, frustrate the obligation to adopt general implementing provisions for the whole of Annex X to the Staff Regulations arising from the third subparagraph of Article 1. Second, the fact that Article 10 of that annex requires ‘provisions for the application’ of that article to be adopted does not preclude those provisions from taking the form of general implementing provisions within the meaning of Article 110 of the Staff Regulations, as the Civil Service Tribunal also previously held in paragraph 26 of the judgment mentioned above. Third, it is not contradictory to provide that general implementing provisions be adopted for the whole of that annex and, in addition, that the opinion of the Staff Committee be obtained before carrying out the annual adjustment of the amount of the ALC in each place of employment.

45

As regards Mr Alba Aguilera and others’ challenge to the admissibility of the first ground of appeal on the ground that it is new and alters the subject matter of the dispute before the General Court, which did not relate to whether the EEAS was obliged to adopt general implementing provisions for Article 10 of Annex X to the Staff Regulations pursuant to the third subparagraph of Article 1 of that annex, but only to whether the EEAS complied with that obligation and whether the decisions of 17 December 2013 and 3 December 2014 constituted such general implementing provisions or could be equated to them, it should be recalled that the Court’s jurisdiction, in an appeal, is limited to a review of the findings of law on the pleas argued at first instance. A party cannot therefore put forward for the first time before the Court of Justice a plea in law which it could have raised before the General Court but did not do so, since that would be to authorise it to bring before the Court of Justice, whose jurisdiction in appeals is limited, a case of wider ambit than that which came before the General Court (see, to that effect, judgments of 1 June 1994, Commission v Brazzelli Lualdi and Others, C‑136/92 P, EU:C:1994:211, paragraph 59, and of 18 February 2016, Council v Bank Mellat, C‑176/13 P, EU:C:2016:96, paragraph 116 and the case-law cited).

46

In the present case, it is true that, in paragraph 25 of the judgment under appeal, the General Court stated that ‘the EEAS does not call into question the fact that it is apparent from the judgment of 17 March 2016, Vanhalewyn v EEAS (T‑792/14 P, EU:T:2016:156), that it was obliged to adopt general implementing provisions relating to Article 10 of Annex X to the Staff Regulations, since the obligation arising under the third subparagraph of Article 1 of that annex also covers the provisions governing the ALC’. In addition, as Mr Alba Aguilera and others submit, the EEAS does not claim that, in paragraph 25, the General Court distorted its argument.

47

Nevertheless, it is apparent from paragraphs 26 and 27 of the judgment under appeal that, before the General Court, the EEAS contested, in essence, the applicability to the present case of the judgment of 17 March 2016, Vanhalewyn v EEAS (T‑792/14 P, EU:T:2016:156). However, that does not prevent the EEAS from challenging, in the present appeal, the interpretation of those provisions of Annex X to the Staff Regulations given by the General Court in the judgment under appeal on the basis of, inter alia, the judgment in Vanhalewyn.

48

Furthermore, in paragraph 26 of their application before the General Court, Mr Alba Aguilera and others submitted, in support of their first plea in law, that ‘it is the third subparagraph of Article [1] of Annex X to the Staff Regulations which expressly lays down the obligation on the institution concerned to adopt general implementing provisions relating to the whole of Annex X to the Staff Regulations’, with the words ‘the whole of Annex X to the Staff Regulations’ also being underlined. They reiterated that argument in paragraph 33 of the application, which states ‘there can be no justification for the EEAS’s delay in complying with its obligation to adopt general implementing provisions for the whole of Annex X to the Staff Regulations’.

49

The General Court reproduced that argument in paragraph 24 of the judgment under appeal, in which it stated that ‘the [applicants at first instance] submit that the EEAS cannot rely on the fact that the judgment of 17 March 2016, Vanhalewyn v EEAS (T‑792/14 P, EU:T:2016:156) was delivered only […] a little more than 1 month before the decision [at issue] was adopted, given that, in any event, the obligation to adopt general implementing provisions for Annex X to the Staff Regulations is laid down in the third subparagraph of Article 1 of that annex’.

50

Under the system governing judicial review proceedings before the EU courts, it is the parties that take the initiative in pursuing the case and delimiting its subject matter (judgment of 14 November 2017, British Airways v Commission, C‑122/16 P, EU:C:2017:861, paragraph 87). Mr Alba Aguilera and others cannot therefore reasonably argue that, by the first ground of appeal, the EEAS is bringing before the Court a dispute of wider ambit that than which they brought before the General Court.

51

In addition, in paragraph 30 of the judgment under appeal, referred to in the first ground of appeal, the General Court held that ‘while Article 10 of Annex X to the Staff Regulations, which is the legal basis for the decision [at issue], does not contain any express stipulation providing for the adoption of general implementing provisions, by contrast, the third subparagraph of Article 1 of Annex X to the Staff Regulations — which falls under Chapter 1 of that annex containing, under ‘General provisions’, special and exceptional provisions applicable to officials serving in a third country — does expressly set out such an obligation’.

52

The General Court concluded, in paragraph 31 of the judgment under appeal, which is also referred to in the first ground of appeal, that ‘the provisions of the third subparagraph of Article 1 of Annex X to the Staff Regulations are of general application and the general implementing provisions it provides are to be adopted concern the whole of Annex X to the Staff Regulations, including the provisions governing the grant of the ALC provided for in Article 10 of Annex X to the Staff Regulations’. In the same paragraph, the General Court added that ‘accordingly, an EU institution implementing those provisions is obliged to adopt general implementing provisions for Article 10 of Annex X to the Staff Regulations in accordance with the third subparagraph of Article 1 of that annex’, and that ‘obligation to adopt general implementing provisions for the whole of Annex X to the Staff Regulations’ was referred to again by the General Court in paragraph 42 of its judgment.

53

In addition, it is clear from an overall reading of the judgment under appeal that it was principally on the basis of that interpretation of the third subparagraph of Article 1 of Annex X to the Staff Regulations that the General Court upheld the first plea in law raised before it.

54

The Court has repeatedly held that an appellant is entitled to lodge an appeal relying, before the Court, on grounds which arise from the judgment under appeal itself and seek to criticise, in law, its correctness (judgments of 29 November 2007, Stadtwerke Schwäbisch Hall and Others v Commission, C‑176/06 P, not published, EU:C:2007:730, paragraph 17, and of 6 September 2018, Czech Republic v Commission, C‑4/17 P, EU:C:2018:678, paragraph 24).

55

It follows from the foregoing that the first ground of appeal is admissible.

56

As set out in the third subparagraph of Article 1 of Annex X to the Staff Regulations, ‘general implementing provisions shall be adopted in accordance with Article 110 of the Staff Regulations’. Article 110(1) provides that ‘the general implementing provisions implementing these Staff Regulations shall be adopted by the appointing authority of each institution after consulting its Staff Committee and the Staff Regulations Committee’.

57

According to the Court’s case-law, recalled, in essence, by the General Court in paragraph 28 of the judgment under appeal, the expression ‘general implementing provisions’ in Article 110(1) of the Staff Regulations refers first and foremost to general implementing provisions expressly provided for by certain special provisions of the Staff Regulations. In the absence of any express stipulation, the obligation to adopt implementing rules subject to the formal requirements of that provision can be recognised only in exceptional circumstances, namely where the provisions of the Staff Regulations are so unclear and imprecise that any application of them must be arbitrary (judgment of 8 July 1965, Willame v Commission, 110/63, EU:C:1965:71, page 815).

58

In the present case, as already set out in paragraphs 51 and 52 above, the General Court held, in essence, in paragraphs 30 and 31 of the judgment under appeal, that the third subparagraph of Article 1 of Annex X to the Staff Regulations constitutes a provision laying down an express obligation to adopt general implementing provisions for all of the provisions of Annex X to the Staff Regulations, including Article 10, within the meaning of the case-law referred to in paragraph 57 of the present judgment, and that the third subparagraph of Article 1 therefore requires, prior to the adoption of a decision revising the amount of the ALC applicable to EU officials and other staff posted abroad, such as the decision at issue, the adoption of general implementing provisions for Article 10 in accordance with the procedure laid down in Article 110 of the Staff Regulations.

59

As EEAS submitted and as is apparent from paragraphs 30 and 31 of the judgment under appeal, the General Court relied, in that regard, on the fact that the third subparagraph of Article 1 of Annex X to the Staff Regulations forms part of the general provisions of that annex.

60

However, it cannot be inferred from that fact that the third subparagraph of Article 1 of Annex X to the Staff Regulations has the scope which the General Court attributed to it.

61

It should be noted that Article 3 of that annex also makes specific reference to the adoption of general implementing provisions, whereas Article 10(3) of that annex is limited to providing that detailed provisions for the application of Article 10 are to be decided by the appointing authority and the fourth subparagraph of Article 10(1) provides that, each year, the review and, where appropriate, the adjustment of the ALC fixed for each place of employment is to be carried out by the appointing authority, after the opinion of the Staff Committee has been obtained. Similarly, Article 2 of Annex X to the Staff Regulations states that detailed implementing rules for the mobility procedure are to be laid down by the appointing authority after consulting the Staff Committee, Article 5(2) of that annex states that detailed rules for the application of Article 5(1) are to be laid down by the appointing authority after consultation of the Staff Committee, and the fourth paragraph of Article 23 of that annex states that detailed rules for the application of that article are to be laid down by the appointing authority. As regards Articles 15 and 21 of that annex, they provide that the benefits they relate to will be granted to the staff concerned on the conditions laid down by the appointing authority.

62

A combined reading of those provisions shows that Annex X to the Staff Regulations refers to the adoption not only of general implementing provisions, but also of ‘detailed rules for the application’ [of a particular provision] and of other types of measure, for which it is in some cases specified that they can be adopted only after consulting the Staff Committee. The wording of Article 110 of the Staff Regulations, in particular the first subparagraph of paragraph 2 and paragraphs 3 and 4, shows that the ‘general implementing provisions’ referred to in paragraph 1 of that article, the adoption of which requires the appointing authority of each institution to consult the Staff Committee and the Staff Regulations Committee, constitute a special category of rules giving effect to the Staff Regulations, which are distinct from rules adopted by agreement between the institutions as well as from other detailed rules for the application of the Staff Regulations.

63

It follows that the system established by the various provisions of the Staff Regulations and Annex X thereto envisages that general implementing provisions be distinguished from other rules giving effect to the Staff Regulations, such as detailed provisions for the application of Article 10(3) of that annex.

64

Furthermore, it should be noted that, in the light of the requirement laid down in Article 110(1) of the Staff Regulations that general implementing provisions can be adopted only after consulting the Staff Committee and the Staff Regulations Committee, the General Court’s interpretation of the third subparagraph of Article 1 of Annex X to the Staff Regulations leads to a duplication of procedural requirements which pursue the same objective.

65

That interpretation thus deprives Article 10(3) of Annex X to the Staff Regulations of at least some of its practical effect, since Article 10(3) lays down less stringent procedural requirements for the adoption of provisions for the application of that article than those resulting from Article 110(1) of the Staff Regulations, as noted, in essence, by the Advocate General in points 41 and 42 of his Opinion.

66

Similarly, the General Court’s interpretation undermines the effectiveness of the other provisions of that annex for which the EU legislature has provided that a special procedure for the adoption of implementing rules, other than that set out in Article 110(1) of the Staff Regulations, is to be followed.

67

By contrast, the factors set out in paragraphs 61 to 66 of the present judgment suggest that the third subparagraph of Article 1 of Annex X to the Staff Regulations must be interpreted as meaning that, where the adoption of general implementing provisions for a provision of that annex is necessary in accordance with the case-law recalled in paragraph 57 above, the third subparagraph of Article 1 specifies the procedure to be followed for the adoption of those provisions, namely that laid down in Article 110 of the Staff Regulations.

68

In support of this, it should be noted, first of all, that Article 3 of Annex X to the Staff Regulations provides that, ‘on the basis of general implementing provisions’, the appointing authority may decide that, by way of derogation from the first subparagraph of Article 1 of that annex, an official posted to a third country who is reassigned temporarily with his post to the seat of the institution or any other place of employment in the Union shall remain subject to certain provisions of that annex for the duration of that temporary assignment.

69

However, if, as the General Court held in the judgment under appeal, the obligation to adopt general implementing provisions for all of the provisions of Annex X to the Staff Regulations already arises from the third subparagraph of Article 1 of that annex, there would have been no need to insert that express provision in Article 3. In that regard, Mr Alba Aguilera and others’ reading of Article 3, described in paragraph 44 of the present judgment, cannot be upheld. It is true that the last sentence of Article 3 introduces a derogation from the first subparagraph of Article 1 of that annex. However, the first subparagraph of Article 1 states that Annex X lays down the special and exceptional provisions applicable to officials of the European Union serving in a third country. It thereby establishes the scope ratione personae of that annex.

70

The derogation is therefore not a derogation from the ‘provisions’ of Annex X to the Staff Regulations, which include the third subparagraph of Article 1 of the annex, which would have the effect of excluding Article 3 of the annex from the third subparagraph of Article 1, as submitted by Mr Alba Aguilera and others, but merely allows the appointing authority to extend, in certain circumstances, the scope ratione personae of Annex X beyond the scope resulting solely from the first subparagraph of Article 1.

71

Next, it must be noted, as the Advocate General has done in points 48 to 54 of his Opinion, that the fact that the third subparagraph of Article 1 of Annex X to the Staff Regulations is merely a procedural reference does not deprive that provision of its effectiveness. In particular, first, that reference remains in any event effective as regards Article 3 of Annex X. Second, the reference is also relevant in the event that it is found that one of the provisions of that annex is so unclear and imprecise that any application of it must be arbitrary and the adoption of general implementing provisions for that provision is therefore necessary.

72

Lastly, the fact that the third subparagraph of Article 1 of Annex X to the Staff Regulations is merely a procedural reference intended to specify the method according to which general implementing provisions are to be adopted is confirmed by the travaux préparatoires which led to Annex X being inserted into the Staff Regulations.

73

Initially, the proposal for a Council Regulation (EEC) laying down special and exceptional provisions applicable to officials of the European Communities serving in a country which does not belong to the European Communities [COM(86) 83 final] (OJ 1986 C 74, p. 11), submitted by the Commission to the Council on 6 March 1986, contained, in Article 1, a single paragraph which now corresponds, in essence, to the first subparagraph of Article 1 of Annex X to the Staff Regulations, and several provisions of that proposal expressly provided for the adoption of general implementing provisions. That was the case, inter alia, with Article 3 of the proposal, which corresponds, in essence, to Article 3 of Annex X to the Staff Regulations, and also with Article 10 of the proposal, which, like Article 10 of Annex X to the Staff Regulations, concerned the ALC. Thus, the proposed Article 10 provided that ‘the general implementing provisions referred to [in that article and in accordance with which the ALC was to be fixed] shall lay down parameters for determining the percentage allowance and shall include a list of the places for which such an allowance is payable and the corresponding rates’.

74

However, the resolution of 12 September 1986 closing the procedure for consultation of the European Parliament on the proposal for the regulation referred to in paragraph 73 above (A2-83/86), attached to the minutes of the sitting of Friday 12 September 1986 (OJ 1986 C 255, pp. 213 and 245), and the amended text proposed in that connection by the Parliament, establish that the Parliament had proposed that the provision which now constitutes the third subparagraph of Article 1 of Annex X to the Staff Regulations be inserted, as such an amendment was, in the Parliament’s view, necessary ‘in order … to specify how implementing provisions may be adopted’.

75

By submitting to the Council on 23 October 1986 an amended proposal for a Council Regulation laying down special and exceptional provisions applicable to officials of the European Communities serving in a country which does not belong to the European Communities (COM(86) 565 final) (OJ 1986 C 284, p. 8), which, in essence, incorporated the Parliament’s proposal, the Commission responded to the amendments proposed by the Parliament.

76

In the version of that regulation that was finally adopted by the Council, namely Council Regulation (Euratom, ECSC, EEC) No 3019/87 of 5 October 1987 laying down special and exceptional provisions applicable to officials of the European Communities serving in a third country (OJ 1987 L 286, p. 3), which added Annex X, in the version resulting from that regulation, to the Staff Regulations, the Parliament’s proposal, which now appears in the third subparagraph of Article 1 of that annex, was retained in the wording that was proposed by the Parliament. In addition, all references to the adoption of general implementing provisions for Article 10 of that annex were deleted, although Article 10 of Annex X to the Staff Regulations, in the version resulting from the amended proposal for a regulation referred to in paragraph 75 above, was rewritten and clarified in order to contain the list of parameters taken into account for fixing the ALC and the weighting applied to those parameters, their value and the scale according to which the allowance was fixed, as a percentage of the reference amount, ranging from 10% where the total value of the various parameters was zero, to 35% where that value was greater than eight. It was also provided, as in the version of that provision currently in force, that the ALC fixed for each place of employment was to be reviewed and, where appropriate, adjusted each year by the appointing authority after the opinion of the Staff Committee had been obtained.

77

Accordingly, it is clear from the travaux préparatoires which led to the insertion of Annex X into the Staff Regulations that, first, the provision now contained in the third subparagraph of Article 1, which has remained unchanged since Regulation No 3019/87, was inserted with the sole objective of specifying the procedure to be followed when general implementing provisions for that annex are to be adopted and that, second, the EU legislature clearly intended to preclude the adoption of general implementing provisions from being necessary in relation to, inter alia, Article 10 of that annex.

78

In that regard, it must also be noted that, until the adoption of Regulation (EU, Euratom) No 1023/2013 of the European Parliament and of the Council of 22 October 2013 amending the Staff Regulations and the CEOS (OJ 2013 L 287, p. 15), Article 10 of Annex X to the Staff Regulations, in the version resulting from Regulation No 3019/87, remained, in essence, unchanged. It was replaced, however, as of 1 January 2014, by the version currently in force, pursuant to Article 1(70)(e) of Regulation No 1023/2013, in order to, as recital 27 of that regulation states, ‘modernise working conditions for staff employed in third countries and to render them more cost-effective whilst generating cost savings …’ and to make provision for ‘the possibility of including a wider range of parameters to fix the [ALC] without affecting the overall aim of generating cost savings’.

79

To that end, Article 10 of Annex X to the Staff Regulations, in the version resulting from Regulation No 3019/87, has been simplified. In essence, the list of parameters to be taken into account when fixing the ALC has been made non-exhaustive, the details relating to the weighting, the values of those parameters and the percentages of the reference amount have been deleted and paragraph 3, under which the appointing authority is to decide the detailed provisions for the application of Article 10, was added.

80

The replacement of Article 10 of Annex X to the Staff Regulations also entered into force on the same day as the replacement — introduced by Article 1(59) of Regulation No 1023/2013 — of Article 110 of the Staff Regulations, the new version of which specifies the various types of rules that may be adopted to give effect to the Staff Regulations.

81

It is therefore equally evident from that latest legislative development that if the EU legislature had intended to require the adoption of general implementing provisions for Article 10 of Annex X to the Staff Regulations, and not the adoption of detailed rules for the application of Article 10, it would have stated so expressly when it simplified the content of that provision.

82

The arguments put forward by Mr Alba Aguilera and others in support of the judgment under appeal, set out in paragraphs 42 to 44 of the present judgment, must therefore be rejected, since they directly contradict the EU legislature’s intention.

83

It follows from all of the foregoing considerations that, by holding, in paragraphs 30 and 31 of the judgment under appeal, that the third subparagraph of Article 1 of Annex X to the Staff Regulations constitutes a provision which lays down an express obligation to adopt general implementing provisions for the whole of that annex and by concluding that the EEAS was required to adopt general implementing provisions for Article 10 of that annex before it could lawfully adopt the decision at issue, the General Court erred in law.

84

Consequently, the first ground of appeal is well founded. However, to the extent that, in accordance with the case-law referred to in paragraph 57 of the present judgment, the obligation to adopt general implementing provisions within the meaning of Article 110 of the Staff Regulations may, in the absence of an express provision to that effect, nevertheless be allowed where the relevant provision of the Staff Regulations is so unclear and imprecise that any application of it must be arbitrary, and to the extent that, by the second ground of appeal, the EEAS claims that, in the judgment under appeal, the General Court also held that Article 10 of Annex X to the Staff Regulations meets that condition, thereby committing a second error of law, the second ground of appeal must be examined before determining whether the judgment under appeal should be set aside to the extent requested.

85

The EEAS, referring to paragraphs 28, 29 and 38 of the judgment under appeal, submits that the General Court erred in law in finding that Article 10 of Annex X to the Staff Regulations is a provision which requires the adoption of general implementing provisions in that it is so unclear and imprecise that any application of it must be arbitrary. The EEAS takes the view that, when adopting implementing rules relating to the ALC, the fourth subparagraph of Article 10(1) of Annex X explicitly and solely requires that the opinion of the Staff Committee be obtained, which is what took place when the decisions of 17 December 2013 and 3 December 2014 were adopted. That step alone eliminates any risk that the criteria for setting the ALC rate be imposed by the authorities on the basis of a specific agenda. The level of detail in Article 10, which sets out the parameters to be taken into account in fixing the ALC and provides for an annual review of those parameters, itself demonstrates that no room is left for arbitrary application.

86

Furthermore, the EEAS submits that the second ground of appeal is effective. Since the obligation to adopt general implementing provisions for Article 10 of Annex X to the Staff Regulations is not expressly provided for by the EU legislature and since the nature of that provision is not such as to require the adoption of general implementing provisions, it is clear that there is no obligation to adopt general implementing provisions for Article 10 of that annex in the sense claimed by Mr Alba Aguilera and others. The second ground of appeal does not relate to the issue of the Staff Committee being consulted or even the relevance of the Staff Committee’s opinion, nor is it tantamount to requiring Mr Alba Aguilera and others to prove a negative.

87

Mr Alba Aguilera and others submit, as their principal plea, that the second ground of appeal is ineffective. Since the General Court rightly held that the third subparagraph of Article 1 of Annex X to the Staff Regulations expressly provides for the obligation for the EEAS to adopt general implementing provisions for Article 10 of that annex, the issue of whether Article 10 is clear is irrelevant.

88

In any event, the second ground of appeal is unfounded. The adoption of general implementing provisions means that the opinion of the Staff Regulations Committee may influence the appointing authority’s decision. Requiring proof of a negative, that is to say, proof that the content of the decision at issue could have been different if general implementing provisions had been adopted, cannot be accepted and renders ineffective the obligation to consult that committee.

89

Since Mr Alba Aguilera and others contest, as their principal plea, the effectiveness of the second ground of appeal, it should be noted that their argument in that regard is based on the premiss that the General Court was right to hold that the third subparagraph of Article 1 of Annex X to the Staff Regulations is a provision which lays down an express obligation to adopt general implementing provisions for all of the provisions of that annex, including Article 10, within the meaning of the case-law referred to in paragraph 57 of the present judgment. However, it follows from the analysis of the first ground of appeal that that premiss is wrong.

90

That being so, it should be noted that, by the second ground of appeal, the EEAS submits, in essence, that the General Court, in paragraph 38 of the judgment under appeal, erred in law in holding that, irrespective of the obligation to adopt general implementing provisions for Article 10 of Annex X to the Staff Regulations, which, in its view, arises from the third subparagraph of Article 1, the nature of Article 10 also requires that, before a decision to adjust the amount of the ALC could lawfully be taken, general implementing provisions must be adopted for Article 10.

91

It is true that, in the first sentence of paragraph 38 of the judgment under appeal, the General Court held that ‘the opinion of an external inter-institutional body, such as the Staff Regulations Committee, is required to ensure that the criteria used to determine the living conditions in third countries are established in the abstract and independently of any procedure the purpose of which is to revise the amount of the ALC, in order to avoid the risk that the criteria chosen might be influenced by the outcome which the authorities hoped to achieve’.

92

However, it is clear from an overall reading of the judgment under appeal, and in particular paragraphs 30, 31, 33 and 40, that the General Court based the annulment of the decision at issue not on the second of the premisses referred to in the case-law recalled in paragraph 57 of the present judgment, but on the fact that, according to the General Court’s interpretation, the third subparagraph of Article 1 of Annex X to the Staff Regulations imposes an express obligation to adopt general implementing provisions for all of the provisions of that annex, including Article 10.

93

Furthermore, as established by paragraphs 34 and 35, the second sentence of paragraph 38 and paragraph 39 of the judgment under appeal, the considerations set out by the General Court in the first sentence of paragraph 38 relate to the issue of whether the decisions of 17 December 2013 and 3 December 2014 may be regarded as general implementing provisions within the meaning of the third subparagraph of Article 1 of Annex X to the Staff Regulations. Accordingly, they relate not to the nature of Article 10 of that annex, but to the General Court’s interpretation of the third subparagraph of Article 1. Moreover, as has already been found, in essence, in paragraph 48 of the present judgment, the first plea for annulment submitted to the General Court concerned only the first of the two premisses referred to in the case-law recalled in paragraph 57 of the present judgment.

94

The second ground of appeal is therefore based on an erroneous reading of the judgment under appeal and, consequently, must be dismissed as unfounded.

95

However, since the first ground of appeal is well founded and the assessment made by the General Court, which the first ground of appeal contends is incorrect, constitutes the basis for the annulment of the decision at issue, as noted inter alia in paragraph 92 of the present judgment, paragraphs 1 and 3 of the operative part of the judgment under appeal must be annulled.

96

In accordance with the first paragraph of Article 61 of the Statute of the Court of Justice of the European Union, the Court may, after quashing the decision of the General Court, itself give final judgment in the matter, where the state of the proceedings so permits, or refer the case back to the General Court for judgment.

97

In the present case, it is apparent from the examination of the appeal that the first plea put forward by Mr Alba Aguilera and others at first instance alleging that the EEAS was, under the third subparagraph of Article 1 of Annex X to the Staff Regulations, required to adopt general implementing provisions for Article 10 of that annex before adopting the decision at issue, is unfounded.

98

However, since the General Court upheld that plea and annulled the decision at issue to the extent requested without examining the second and third pleas put forward before it, the Court considers that the state of the proceedings does not permit a decision by the Court. Accordingly, the case must be referred back to the General Court.

99

Since the case is being referred back to the General Court, it is appropriate to reserve the costs.

On those grounds, the Court (Tenth Chamber) hereby: