JOHANNESBURG, South Africa – South Africa’s highest court ruled in favor of gay marriage yesterday, a landmark decision that clears the way for the country to become the first to legalize same-sex unions on a continent where homosexuality remains largely taboo.

The decision does not take immediate effect, however. The Constitutional Court, which decided it is unconstitutional to prohibit gays from marrying, gave Parliament a year to make the necessary legal changes. That disappointed gay rights activists, some of whom have been waiting years to wed.

“We were thinking we would be calling our friends today and inviting them to our wedding,” said Fikile Vilakazi, of the Forum for the Empowerment of Women, who proposed to her partner more than six months ago. “Now they are asking us to wait another year.”

Canada, the Netherlands, Belgium, and Spain are the only countries that now allow gay marriage nationwide.

South Africa recognized the rights of gay people in the constitution adopted after apartheid ended in 1994 – the first in the world to prohibit discrimination on the basis of sexual orientation. But the government has opposed attempts to extend the definition of marriage in court to include same-sex couples in the mostly Christian country.

Married couples have many rights denied gay couples, including the ability to make decisions on each other’s behalf in medical emergencies and inheritance rights if a partner dies without a will.

In delivering yesterday’s ruling, Judge Albie Sachs said current legal definitions of marriage as a union between a man and a woman “are accordingly inconsistent with sections … of the Constitution to the extent that they make no provision for same-sex couples to enjoy the status, entitlements and responsibilities they accord to heterosexual couples.”

The court instructed Parliament to extend the legal definition within a year, or else the courts would automatically do so, the South African Press Association reported.

Yesterday’s ruling was in response to a government appeal against a Supreme Court ruling last year that said a lesbian couple’s union should be recognized.

There was no immediate government comment on the decision.

Marie Fourie and Cecelia Bonthuys, a couple from Pretoria, took their case to court after the government refused to recognize their October 2002 wedding on the basis of the common-law definition of marriage. They were not in court yesterday.