The California Supreme Court decided unanimously Monday that illegal immigrants may continue to be eligible for in-state tuition rates at the state's colleges and universities rather than pay the higher rates charged to those who live out of state.

In a ruling written by Justice Ming W. Chin, one of the panel's more conservative members, the state high court said a California law that guarantees the lower tuition for students who attend California high schools for at least three years and graduate does not conflict with a federal prohibition on giving illegal immigrants educational benefits based on residency.

California is one of several states that permit illegal immigrants to take advantage of lower college tuition for students who attend high school and graduate in state. About 25,000 illegal immigrants are estimated to receive in-state tuition rates in California.

A group fighting illegal immigration challenged the California law on behalf of U.S. citizens who pay the higher tuition as out-of-state students. The group won in lower court, and the state appealed.