4) The review concerns the question whether, having regard, in particular, to the general principle of legal certainty, the judgments under review affect the unity or consistency of EU law in so far as the General Court, as court of appeal, held that the composition of the panel of judges of the Civil Service Tribunal which had made the order of 24 June 2016, Simpson v Council (F‑142/11 RENV, EU:F:2016:136), and the judgment of 19 July 2016, HG v Commission (F‑149/15, EU:F:2016:155) (together, ‘the contested decisions’), had been irregular, on the basis of an irregularity affecting the procedure for the appointment of one of the members of that panel of judges, leading to a breach of the principle of the lawful judge, laid down in the first sentence of the second paragraph of Article 47 of the Charter of Fundamental Rights of the European Union (‘the Charter’).

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6) Article 47 of the Charter, entitled ‘Right to an effective remedy and to a fair trial’, states, in the first and second paragraphs thereof:

‘Everyone whose rights and freedoms guaranteed by the law of the Union are violated has the right to an effective remedy before a tribunal in compliance with the conditions laid down in this Article.

Everyone is entitled to a fair and public hearing within a reasonable time by an independent and impartial tribunal previously established by law. Everyone shall have the possibility of being advised, defended and represented.’

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43) Thirdly, in paragraph 78 of the judgment of 23 January 2018, FV v Council (T‑639/16 P, EU:T:2018:22), the General Court held that in the light of the importance of observing the rules governing the appointment of a judge with regard to litigants’ confidence and that of the public in the independence and impartiality of courts and tribunals, the judge concerned could not be regarded as a judge assigned by law for the purposes of the first sentence of the second paragraph of Article 47 of the [Charter] and, therefore, set aside the judgment of 28 June 2016, FV v Council (F‑40/15, EU:F:2016:137) in its entirety.

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46) Accordingly, the order under appeal must be set aside in its entirety on the grounds of infringement of the principle of the right to a judge assigned by law, enshrined in the first sentence of the second paragraph of Article 47 of the [Charter], without it being necessary to examine the grounds of appeal raised by the appellant.’

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50) As regards the answer to the question to be reviewed in this case, it is necessary to begin by examining whether, having regard, in particular, to the general principle of legal certainty, the General Court erred in law by setting aside the contested decisions on the ground that the composition of the panel of judges of the Civil Service Tribunal which had delivered those decisions had been irregular because of an irregularity affecting the procedure for the appointment of one of the members of that panel of judges, leading to a breach of the principle of the lawful judge, laid down in the first sentence of the second paragraph of Article 47 of the Charter.

51) In the context of that examination, it is necessary to determine, first, in what circumstances the appointment of a judge may, like acts covered by Article 277 TFEU, form the subject matter of an incidental review of legality. Secondly, the Court must verify whether, in so far as the irregularity concerning the appointment procedure is established, as determined by the General Court, that irregularity did indeed lead to an infringement of the first sentence of the second paragraph of Article 47 of the Charter, justifying the setting aside of those decisions.

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55) However, it follows from the fundamental right to an effective remedy before an independent and impartial tribunal previously established by law, guaranteed by Article 47 of the Charter, that everyone must, in principle, have the possibility of invoking an infringement of that right. Accordingly the Courts of the European Union must be able to check whether an irregularity vitiating the appointment procedure at issue could lead to an infringement of that fundamental right.

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69) In the judgments under review, the General Court, again relying on the judgment of 23 January 2018, FV v Council (T‑639/16 P, EU:T:2018:22), held that in the light of the importance of observing the rules governing the appointment of a judge with regard to litigants’ confidence and that of the public in the independence and impartiality of courts and tribunals, the judge appointed to the third post could not be regarded as a lawful judge for the purposes of the first sentence of the second paragraph of Article 47 of the Charter.

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72) Since the first sentence of the second paragraph of Article 47 of the Charter corresponds to the first sentence of Article 6(1) of the Convention for the Protection of Human Rights and Fundamental Freedoms, signed in Rome on 4 November 1950 (‘ECHR’), its meaning and scope are, in accordance with Article 52(3) of the Charter, the same as those laid down by that convention. The Court must therefore ensure that the interpretation which it gives to the second paragraph of Article 47 of the Charter safeguards a level of protection which does not fall below the level of protection established in Article 6 ECHR, as interpreted by the European Court of Human Rights (judgment of 19 November 2019, A. K. and Others(Independence of the Disciplinary Chamber of the Supreme Court), C‑585/18, C‑624/18 and C‑625/18, EU:C:2019:982, paragraph 118 and the case-law cited).

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75) It follows from the case-law cited in paragraphs 71 and 73 of the present judgment that an irregularity committed during the appointment of judges within the judicial system concerned entails an infringement of the first sentence of the second paragraph of Article 47 of the Charter, particularly when that irregularity is of such a kind and of such gravity as to create a real risk that other branches of the State, in particular the executive, could exercise undue discretion undermining the integrity of the outcome of the appointment process and thus give rise to a reasonable doubt in the minds of individuals as to the independence and the impartiality of the judge or judges concerned, which is the case when what is at issue are fundamental rules forming an integral part of the establishment and functioning of that judicial system.

76) It is in the light of those principles that the Court must examine whether the irregularity committed in the appointment procedure at issue resulted in this instance in an infringement of the parties’ right to a hearing by a tribunal previously established by law, as guaranteed by the first sentence of the second paragraph of Article 47 of the Charter.

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81) It follows from the foregoing that the Council’s disregard for the public call for applications of 3 December 2013 does not constitute an infringement of the fundamental rules of EU law applicable to the appointment of judges to the Civil Service Tribunal that entailed an infringement of the applicants’ right to a tribunal established by law, as guaranteed by the first sentence of the second paragraph of Article 47 of the Charter.

82) Consequently, and since the judgments under review do not contain anything else that might cast doubt on compliance with the first sentence of the second paragraph of Article 47 of the Charter, it must be held that the General Court made an error of law in ruling, in those judgments, that that provision had been infringed. The irregularity referred to in the preceding paragraph could not, therefore, by itself justify the setting aside of a judicial decision adopted by the panel of judges to which the judge appointed to the third post was assigned.

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85) The judgments under review could constitute precedents for future cases, since the General Court’s erroneous interpretation and application of the first sentence of the second paragraph of Article 47 of the Charter could have repercussions for other cases in which the appointment of a member of a panel of judges and, more generally, the right to an independent and impartial tribunal previously established by law is put in issue.

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87) In those circumstances, it must be held that the judgments under review affect the unity and consistency of EU law in so far as the General Court, as court of appeal, held that the composition of the panel of judges of the Civil Service Tribunal which had delivered the contested decisions had been irregular, on the basis of an irregularity affecting the procedure for the appointment of one of the members of that panel of judges, leading to a breach of the principle of the lawful judge, laid down in the first sentence of the second paragraph of Article 47 of the Charter, and set aside those decisions.

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90) Since, in the judgments under review, the General Court set aside the contested decisions on the basis of an infringement of the first sentence of the second paragraph of Article 47 of the Charter without examining the grounds of appeal which the appellants had put forward in their respective appeals, the judgments under review must be set aside and the cases referred back to the General Court in order for it to rule on those grounds of appeal.

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92) Since there are no specific rules governing orders for costs in the case of a review, the parties must be ordered to bear their own costs.

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

1. Orders that Cases C‑542/18 RX‑II and C‑543/18 RX‑II be joined for the purposes of the judgment;
2. Declares that the judgments of the General Court of the European Union (Appeal Chamber) of 19 July 2018, Simpson v Council (T‑646/16 P, not published, EU:T:2018:493) and HG v Commission (T‑693/16 P, not published, EU:T:2018:492) affect the unity and consistency of EU law in so far as the General Court, as court of appeal, held that the composition of the panel of judges of the European Union Civil Service Tribunal which had delivered the order of 24 June 2016, Simpson v Council (F‑142/11 RENV, EU:F:2016:136) and the judgment of 19 July 2016, HG v Commission (F‑149/15, EU:F:2016:155), respectively, had been irregular, on the basis of an irregularity affecting the procedure for the appointment of one of the members of that panel of judges, leading to a breach of the principle of the lawful judge, laid down in the first sentence of the second paragraph of Article 47 of the Charter of Fundamental Rights of the European Union, and set aside those decisions;
3. Sets aside those judgments;
4. Refers the cases back to the General Court of the European Union;
5. Orders Mr Erik Simpson, the Council of the European Union, HG, the European Commission and the Bulgarian Government to bear their own costs in relation to the review proceedings.