The Constitutional Court of the Republic of Lithuania ensures the supremacy of the Constitution within the legal system as well as constitutional justice by deciding whether the laws and other legal acts adopted by the Seimas are in conformity with the Constitution, and whether the acts adopted by the President of the Republic or the Government are in compliance with the Constitution and laws.

The Constitutional Court does not perform any preliminary judicial review of laws. The Constitutional Court decides the constitutionality issues of enacted laws and other legal acts (a posteriori control). The Constitutional Court examines a case only when the subjects prescribed by the Constitution address the Constitutional Court with a petition requesting for the determination of the conformity of a law or a legal act with the Constitution.

The right to file a petition with the Constitutional Court for an investigation into the constitutionality of a legal act is vested in: (1) the Government, a group of not less than 1/5 of all the members of the Seimas, and courts concerning a law or another act adopted by the Seimas; (2) a group of not less than 1/5 of all the members of the Seimas and courts concerning an act of the President of the Republic; and (3) a group of not less than 1/5 of all the members of the Seimas, courts, and the President of the Republic concerning an act of the Government.

The right to file a petition with the Constitutional Court concerning the constitutionality of all above-mentioned legal acts is also granted to every person if he or she believes that a decision adopted on the basis of such a legal act has violated his or her constitutional rights or freedoms, and the person has exhausted all legal remedies. Such a person may apply to the Constitutional Court only when, in the case concerning the decision violating his or her constitutional rights or freedoms, the final and non-appealable decision on the merits of the case or on rejecting the complaint is adopted by a court of general competence or administrative court, i.e. such a decision of a court is adopted that precludes any further defence of the violated rights or freedoms of the person before the courts of general competence or administrative courts. A petition concerning the violated constitutional rights or freedoms may be filed with the Constitutional Court not later than within 4 (four) months of the day that the final and non-appealable decision of the court came into force.

The Constitutional Court gives rulings in cases concerning the compliance of laws and acts of the Seimas, the President of the Republic, and the Government.

The case for a hearing of the Constitutional Court is prepared by the justice-rapporteur appointed by the President of the Court. At the beginning of Constitutional Court’s hearing the Court announces which of the summoned persons are present, informs parties to the case of their rights and duties, hears and settles requests of parties to the case. The justice-rapporteur delivers their report in which the substance of the case is presented. After this, the statements of the parties to the case are heard, the evidence is examined and court pleadings take place. The ruling must be made within one month after the end of the investigation of the case. After the Court’s hearing the Constitutional Court retires to the deliberation room to make a ruling.

Rulings of the Constitutional Court are pronounced in the name of the Republic of Lithuania. The Constitutional Court’s decisions defined by the Constitution as falling within the Constitutional Court’s competence are final and not subject to appeal. Rulings of the Constitutional Court have the power of law and are obligatory for all institutions of authority, courts, all enterprises, establishments and organisations, officials and citizens (erga omnes).

Under the Constitution, laws of the Republic of Lithuania (or a part thereof) or other Seimas acts (or a part thereof), acts of the President of the Republic, or acts of the Government (or a part thereof) shall not be applicable from the day that a ruling of the Constitutional Court stating that the appropriate act (or a part thereof) conflicts with the Constitution of the Republic of Lithuania is officially published (ex nunc).

The force of a ruling of the Constitutional Court recognising a legal act (or a part thereof) unconstitutional may not be overcome by repeated enactment of an equivalent legal act (or a part thereof).

The Constitutional Court also gives the following conclusions: (1) whether there were violations of election laws during elections of the President of the Republic or elections of members of the Seimas; (2) whether the state of health of the President of the Republic allows him to continue to hold office; (3) whether international treaties of the Republic of Lithuania are not in conflict with the Constitution; (4) whether concrete actions of members of the Seimas and State officials against whom an impeachment case has been instituted are in conflict with the Constitution.

The Seimas may request that the Constitutional Court give a conclusion. The President of the Republic may address the Constitutional Court for a conclusion concerning the election of members of the Seimas and regarding international treaties. The conclusion concerning international treaties may be requested already prior to its ratification in the Seimas. The Seimas, conforming to conclusions of the Constitutional Court, adopts the final decision.

The Constitutional Court investigates and decides only legal issues and refuses to consider petitions for the examination of the constitutionality of a legal act if the petition is grounded upon non-legal reasoning.