The Fundamental Law of Hungary (Hungarian: Magyarország alaptörvénye), the country's constitution, was adopted by parliament on 18 April 2011, promulgated by the president a week later and entered into force on 1 January 2012.

Among the claims critics make are that it was adopted without sufficient input from the opposition and society at large, that it reflects the ideology of the ruling Fidesz party, and enshrines it in office, that it is rooted in a conservative Christian worldview despite Hungary not being a particularly devout country, and that it curtails and politicizes previously independent institutions.

[5][4] The life of a fetus is protected from the moment of conception, and although the move is seen as opening the possibility for a future ban or restrictions on abortion,[4] existing laws were unaffected.

[12] Laws affecting areas such as family policy, the pension system and taxation can be altered only through special legislation (cardinal acts) passed by a two-thirds majority of Parliament and are not subject to constitutional review.

[17] Following the advent of the Hungarian Soviet Republic, the Revolutionary Governing Council adopted a Provisional Constitution on 2 April 1919, providing for a Soviet-style political system.

[33] Provisions were then included or excluded based on consensus among respondents; for instance, a proposal to adopt voting rights for minors was shelved after citizens expressed disapproval.

[34] The following April 18, Parliament approved the constitution by the required two-thirds majority, on a 262–44 vote, with Fidesz and their Christian Democrat coalition partners in favor and Jobbik opposed.

[5] According to Fidesz parliamentary group chairman János Lázár, the constitution marks a break with Hungary’s communist past,[5] while Prime Minister Viktor Orbán said it completes a transition to democracy and allows for sound finances and clean government after years of mismanagement and scandals.

[12] Members of the Hungarian business community mentioned possible future difficulties in adopting the euro, noting a provision that enshrines the forint as legal tender.

[36] One section of the preamble criticized by some historians as well as by the head of Hungary's Jewish community is the statement that the country lost its independence when it was invaded and occupied by Nazi Germany in March 1944.

They asserted that the provision implies the state was not responsible for the ensuing deportation of Jews to extermination camps as part of the Holocaust and that it could affect future restitution claims.

[37] Historian Géza Jeszenszky strongly rejected criticism of the passage, saying the loss of Hungarian sovereignty in March 1944 due to foreign invasion is simply a historical fact that should not be denied.

Outside on Andrássy út, tens of thousands of people protested the occasion, with opponents claiming the constitution threatens democracy by removing checks and balances.

Fidesz MP Gergely Gulyás, who helped write the constitution, responded to critics by saying that it improves the legal framework of life in Hungary.

[11] Among these was Guy Verhofstadt, head of the Alliance of Liberals and Democrats for Europe, who said the constitution could limit "fundamental human rights" and was adopted without transparency, flexibility, a spirit of compromise and sufficient time for debate.

[49][50] Subsequently, President János Áder signed the amendment into law, citing his legal duty and the need to preserve national unity.

The Socialist floor leader labeled the measure an attempt to restrict the Constitutional Court's powers, and party members hung black flags from the Hungarian Parliament Building's windows, in sign of mourning for democracy.

The LMP charged that the government was "dismantling constitutional values", while former prime minister Ferenc Gyurcsány, head of the small Democratic Coalition, also drew attention to the diminution in the court's prerogatives.

[55] José Manuel Barroso, President of the European Commission, and Thorbjørn Jagland, Secretary General of the Council of Europe, together raised concerns about the amendment's impact on the rule of law,[56] while prominent EU politicians, including Verhofstadt and Martin Schulz, expressed more forceful criticism.