(a)

Does the general statutory duty, or the administrative obligation directed at individual carriers, not to bring into federal territory foreign nationals not in possession of a passport or residence permit as required, which is properly discharged only if carriers check all passengers’ travel documents before crossing an internal border, constitute, or fall to be treated as, a check on persons at internal borders within the meaning of Article 22 of the Schengen Borders Code?

(b)

Is the imposition of the duties referred to in point 1 to be assessed by reference to Article 23(a) of the Schengen Borders Code, even though carriers do not exercise ‘police powers’ within the meaning of that provision and, moreover, do not formally enjoy any powers of public authority by virtue of the State-imposed obligation to carry out checks?

(c)

If the answer to Question 1(b) is in the affirmative, do the checks which carriers are required to carry out, taking into account the criteria laid down in the second sentence of Article 23(a) of the Schengen Borders Code, constitute an impermissible measure having an effect equivalent to border checks?

(d)

Is the imposition of the duties referred to in point 1, in so far as it concerns bus undertakings operating regular services, to be assessed by reference to Article 23(b) of the Schengen Borders Code, which provides that the absence of border control at internal borders is not to affect the power of carriers to carry out security checks on persons at ports and airports? Does it follow from this that checks within the meaning of Question 1 are impermissible even when carried out other than at ports and airports if they do not constitute security checks and are not also carried out on persons travelling within a Member State?