Portugal's highest court ruled on Thursday that the country's proposed same-sex marriage law should be enacted, which leaves only the president's signature as the last step before the bill becomes a law.

Portuguese president Anibal Cavaco Silva, a conservative, sent the Parliament-approved bill to the constitutional court last month after he had apprehensions over the constitutionality of the bill. He now has 20 days to sign the legislation.

Tribunal president Rui Moura Ramos said that while the marriage equality bill does not conform to the concept of marriage laid out in the current constitution, he agreed that the concept is open to interpretation and evolution, according to Euro News.

If signed into law, Portugal would become the sixth European nation to legalize same-sex marriage.