The Costa Rican Supreme Court ruled Wednesday that legislation banning same-sex marriage is unconstitutional, citing a ruling last January from the Inter-American Court of Human Rights.

Last January, the Inter-American Court established the obligation for the signatory states of the Inter-American Convention on Human Rights (IACHR)—an organ of the Organization of American States (OAS)—to take the necessary measures to allow homosexual marriage under the same conditions as marriages between a man and a woman.

The January 8 decision, which set binding precedent in signatory countries, ruled that the 1969 American Convention on Human Rights mandates the legalization of same-sex marriage. The ruling applies to the countries of Barbados, Bolivia, Chile, Costa Rica, the Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, and Suriname.

In Wednesday’s ruling, the Costa Rican justices gave the country’s Legislative Assembly a period of 18 months to modify the Costa Rican legal framework, following the ruling of the IACHR, which provides for a time frame “to adapt their systems, interpretations and internal practices.”

Even if the Legislative Assembly fails to adopt new marriage laws within 18 months, same-sex marriage will automatically be legalized at that time, since the court has established the unconstitutionality of the current legislation, said justice Fernando Castillo at a press conference.

“If the parliament does not act, then according to the vote that law would become invalid and cease to exist, and if there is no prohibition, the possibility for homosexuals to marry is authorized,” he said.

Deputy Jonathan Prendas, an evangelical Christian, expressed his displeasure at the court’s judicial activism that has taken lawmaking out of the hands of elected officials.

The court’s decision has “put a gun to our heads” to change the existing law, he said.

The nation’s first openly gay deputy, Enrique Sánchez, told AFP that he doesn’t believe that the assembly will manage an agreement to change the law in 18 months.

Mr. Sanchez belongs to the progressive Citizens’ Action Party (PAC), headed by Costa Rica’s current president Carlos Alvarado, a former novelist and singer in a rock band who was elected in April after a campaign that pushed the topic of LGBT rights.

For his part, President Alvarado welcomed the decision: “We will continue to push for actions that guarantee non-discrimination of people because of their sexual orientation or gender identity, and state protection to all families on equal terms,” he wrote on Twitter.

Same-sex marriage continues to be illegal in Belize, Bolivia, Ecuador, El Salvador, Guatemala, Guyana, Honduras, Nicaragua, Panama, Paraguay, Peru, Suriname, and Venezuela, as well as on most of the Caribbean Islands.

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