The U.S. Supreme Court will take up the issue of gay marriage for the first time, agreeing to rule on a California ballot measure banning the practice and a federal law defining marriage as solely an opposite-sex union.

The cases, which the court will decide by June, loom as a potential turning point on one of the country’s most divisive issues. High court review comes as the gay-marriage movement is showing unprecedented momentum, winning victories at the polls in four states this year.

The California dispute will address whether gay marriage is legal in the most populous U.S. state, home to more than 37 million people. The case also gives the justices a chance to go much further and tackle the biggest issue: whether the Constitution guarantees same-sex marriage rights nationwide.

That question is “perhaps the most important remaining civil rights issue of our time,” saidTheodore Olson, a Washington lawyer leading the legal fight against the California measure.

Read more at Bloomberg