A lesbian couple was the first to wed Monday as Portugal's gay marriage law came into force, the AP reported.

Teresa Pires and Helena Paixao tied the knot in a Lisbon registry office. The ceremony was attended by about 30 people.

The women first attempted to marry in 2006, taking their fight all the way to the nation's Constitutional Court.

In 2009, the court narrowly ruled against the women, saying the constitution does not explicitly permit such marriages despite its prohibition against discrimination based on sexual orientation.

“It shows there is a change coming,” Paixao said at the time about the split decision. “Bit by bit people will come around” to accept gay marriage.

Beginning Monday, marriage in Portugal is defined as a “contract between two people wishing to form families through the full communion of life.”

Prime Minister Jose Socrates, a Social Democrat, promised to legalize gay marriage if his party was returned to power. Lawmakers approved the bill in February.

Portugal's conservative president, Anibal Cavaco Silva, reluctantly signed the gay marriage bill into law on May 17, saying he was only doing so because Social Democrats were certain to overturn a veto.

Social conservatives had urged the president to veto the bill. Pope Benedict condemned the institution as he toured the predominantly Roman Catholic nation just days before the president ratified the law. Speaking in the city of Fatima, the pope called gay marriage “insidious and dangerous” and urged Catholics to stand united in opposition.

The new law prohibits gay and lesbian couples from adopting.

After the ceremony, Pires called her marriage “a dream come true.” The couple said they would continue to fight for additional rights, including adoption.

Portugal joins five European countries – Belgium, the Netherlands, Spain, Norway and most recently Sweden – in legalizing gay marriage.

Lawmakers in Iceland and Argentina are also debating the issue.