Treaty on European Union (TEU): Article 2 (values of the Union, including respect for the rule of law), Article 4(3) (principle of sincere cooperation), Article 19(1) (obligation of Member States to provide remedies sufficient to ensure effective legal protection in the fields covered by Union law).
Treaty on the Functioning of the European Union (TFEU)
Charter of Fundamental Rights of the European Union: Article 47 (right to an effective remedy and to a fair trial).

Case C-824/18: Concerning the independence of the judiciary and the conditions under which national courts may disregard national laws that conflict with EU law.
Case C-619/18: Related to the independence of the judiciary and the obligation of Member States to ensure effective legal protection in the fields covered by Union law.
Cases C-585/18, C-624/18, C-625/18: Addressing issues related to the disciplinary regime for judges and the principle of judicial independence.
Case C-487/19: Discussing the requirements of judicial independence and the effective functioning of the judicial system in Member States.
Case C-791/19: Concerning the European Commission's action against Poland for alleged violations of EU law related to judicial independence.

The reasoning in the judgment K 3/21 of the Polish Constitutional Tribunal centers on the constitutionality of specific EU laws and the principles arising from them in relation to the Polish Constitution. The Tribunal addresses whether certain provisions of the EU treaties, as interpreted by the Court of Justice of the European Union (CJEU), are consistent with the Polish Constitution.

Legal Reasoning:

Primacy of National Constitution:
The Tribunal reaffirms the primacy of the Polish Constitution over EU law. It argues that while Poland respects its obligations under EU law, this respect does not extend to allowing EU institutions to overstep their competences as defined by the Polish Constitution. Specifically, it states that the Polish Constitution remains the supreme law of the land and any conflict between national law and EU law should be resolved in favor of the Polish Constitution.

Judicial Independence and Structure:
The Tribunal scrutinizes the EU's influence on the Polish judicial system, particularly the procedures for appointing judges. It argues that EU institutions, primarily the CJEU, lack competence to regulate or assess the appointment and removal of Polish judges. This domain is reserved exclusively for Polish authorities under the Constitution. The judgment refers to the constitutional provisions that outline the role of the President and the National Council of the Judiciary in appointing judges, emphasizing that these processes should not be subject to external interference.

Articles of the Polish Constitution:
The Tribunal invokes several constitutional articles:

Article 2: Principles of a democratic state ruled by law.
Article 8: Supreme legal force of the Constitution.
Article 90: Conditions for delegating competences to international organizations.
Article 144(3)(17): Presidential prerogative to appoint judges.
Article 178(1): Independence of judges.
Article 186(1): Role of the National Council of the Judiciary in safeguarding the independence of courts and judges.
Article 190(1): Finality and binding force of the Tribunal’s judgments.

Conflict with EU Law:
The Tribunal identifies specific provisions and interpretations of EU law that it deems incompatible with the Polish Constitution. It highlights Article 19(1) of the Treaty on European Union (TEU) and Article 2 of the TEU, as interpreted by the CJEU, particularly in the context of the rule of law and judicial independence. The Tribunal asserts that these interpretations intrude upon national sovereignty and the constitutional order of Poland.

CJEU Jurisprudence:
The Tribunal critically analyzes several CJEU rulings that have influenced Polish judiciary reforms. It points to decisions such as:

C-619/18 (Commission v. Poland): This ruling found that Poland's law lowering the retirement age of Supreme Court judges was inconsistent with EU law as it undermined judicial independence.
C-192/18 (Commission v. Poland): Here, the CJEU ruled against Poland's measures concerning the lowering of the retirement age of ordinary court judges.
C-585/18, C-624/18, and C-625/18 (A.K. v. Krajowa Rada Sądownictwa): The CJEU ruled that the newly established Disciplinary Chamber of the Supreme Court does not meet the requirements of judicial independence under EU law.
C-824/18 (A.B. and Others): The CJEU held that national courts must disregard provisions of national law that preclude them from reviewing whether a court is independent under EU standards.
These decisions, according to the Tribunal, unlawfully expand the CJEU's jurisdiction into areas of national judicial appointments and disciplinary proceedings for judges. The Tribunal argues that such rulings exceed the competences conferred upon the EU and undermine the constitutional authority of Polish institutions.
European Charter of Fundamental Rights and ECHR:
The judgment does not directly analyze the European Charter of Fundamental Rights or the European Convention on Human Rights (ECHR). However, it implicitly contests interpretations of these instruments by the CJEU and the European Court of Human Rights (ECtHR) that conflict with Polish constitutional principles. The Tribunal emphasizes that while Poland respects international human rights obligations, these must be interpreted in a manner consistent with the national constitution.

Conclusion:
The Polish Constitutional Tribunal, in its judgment K 3/21, concludes that certain provisions and interpretations of EU law, particularly those pertaining to judicial appointments and the disciplinary regime for judges, are incompatible with the Polish Constitution. It underscores the supremacy of the Polish Constitution and asserts the necessity for EU law to respect national constitutional identities and limits of conferred competences. This judgment reaffirms Poland's commitment to its constitutional sovereignty and delineates the boundaries of EU influence on its legal and judicial framework.

Relation of the Case to the EU Charter:

The EU Charter of Fundamental Rights was explicitly invoked in the judgment K 3/21 by the Polish Constitutional Tribunal, particularly Article 47, which guarantees the right to an effective remedy and a fair trial. The Tribunal analyzed this provision in the context of its compatibility with the Polish Constitution and the principles governing the Polish judicial system.

Analysis:
1. Article 47 of the EU Charter:
   The Polish Constitutional Tribunal referred to Article 47 of the EU Charter multiple times. Article 47 ensures the right to a fair trial and effective judicial protection, which aligns with the principles of judicial independence and impartiality. However, the Tribunal emphasized that while these principles are important, they must be interpreted within the framework of the Polish Constitution.

2. Conflict with National Law:
   The Tribunal argued that certain interpretations of Article 47 by the CJEU, particularly those that challenge national procedures for judicial appointments and dismissals, conflict with the Polish Constitution. The Tribunal maintained that the Polish Constitution provides comprehensive safeguards for judicial independence and effective legal remedies, consistent with Article 47 of the EU Charter.

3. Use of the Charter in the Judgment:
   The EU Charter was used to support the Tribunal’s reasoning but not as a legally binding parameter that overrides the Polish Constitution. The Tribunal acknowledged the Charter’s principles but insisted that their application must respect national sovereignty and constitutional identity.

4. CJEU Jurisprudence:
   The Tribunal referenced several CJEU judgments that invoked Article 47 to assert broader EU oversight over national judicial systems. The Tribunal critiqued these judgments for overstepping the competences conferred upon the EU and undermining the constitutional provisions of member states.

Conclusion:
The EU Charter of Fundamental Rights, specifically Article 47, was invoked in the Polish Constitutional Tribunal’s judgment K 3/21. The Tribunal used Article 47 to frame its argument about judicial independence and effective legal remedies but emphasized that these principles must be applied in a manner consistent with the Polish Constitution. Thus, while the Charter was used to support the reasoning, it was not employed as a legally binding parameter that could override national constitutional provisions.