MEXICO CITY, Mexico (CNN) -- Mexico's highest court voted 8-3 Thursday to uphold women's right to abortion in the capital.
"This is a momentous decision and legal victory for women and families in Mexico," said Lilian Sepúlveda, regional manager and legal adviser for Latin America and the Caribbean at the Center for Reproductive Rights.
"In a region where abortion is highly restricted, the Supreme Court has taken a huge leap forward in protecting women's basic human rights. Today's ruling opens the door for women across the country to demand that their local governments follow Mexico City's example."
A representative of the Catholic church, which opposes abortion, said it would ring the bells of the city's cathedral in mourning. Mexico is overwhelmingly Roman Catholic.
Four of the 11 Supreme Court ministers would have been needed to invalidate last year's changes that allowed first-trimester abortions in Mexico City.
Outside Mexico City, abortion is legal only in cases of rape, if the mother's life is in danger or if the fetus is badly deformed.
In 2007, Mexico City's leftist government legalized abortions in the first 12 weeks of pregnancy. The federal Attorney General's Office and National Human Rights Commission took the law to the Supreme Court, arguing that the city can't make health laws.
Thursday's vote by the justices formalized their rejection of the proposal put forth by Aguirre Sandino, one of the ministers, who argued that the law is unconstitutional because life begins at conception and should therefore be protected from that time forward.
But his fellow ministers did not agree.
"The ministers that voted against his proposal say there is no place explicitly in the Mexican constitution or in international law that says life should be protected from the moment of conception," said Maria Luisa Sanchez Fuentes, executive director of the Information Group on Reproductive Choice, who was one of about 150 people inside the courtroom.
"There is always a flexibility and exceptions," she said, citing the right to kill in self-defense or to carry out a hunger strike.
Those who defend the current law say it has helped save the lives of hundreds of young women who otherwise would have sought abortions at clandestine, unsafe clinics.
Many Mexicans have said they believe that the right to an abortion means a woman is more like to be promiscuous.
Brenda Velez, 38, visits an abortion clinic four times a week to recite the rosary, according to The Association Press. "They are just encouraging women to be dirty and loose," she said. "The justices' decision is only going to spread more irresponsible behavior."
Serrano Limon, an anti-abortion advocate, said legalized abortion "gave legality to these pseudo-doctors to open their clinics and continue operating as they are doing, and now, they're no longer doing it in secret, they're doing it openly."
The law applies only to Mexico City's public hospitals. It also allows doctors with moral objections to refuse to do the procedure and does not require doctors in federal hospitals or private clinics to perform abortions, the AP reports.
Before abortion was legalized, many women turned to an herbal tea capable of inducing abortion, the AP said, and also sought out people who performed crude procedures to terminate a pregnancy.