California will ban private colleges and universities, including some of the nation’s most selective institutions, from giving special consideration to applicants who have family or other connections to the schools, a practice known as legacy preferences.

Gov. Gavin Newsom signed legislation on Monday that will prohibit the practice starting in the fall of 2025.

The prohibition, which will affect Stanford University, the University of Southern California and others, comes at a time when institutions nationwide have been rewriting their admissions rules to reflect a Supreme Court ruling last summer that banned race-based considerations in the college admissions process. That case, which focused on affirmative action, revealed the extent to which legacy status has played a role in selection at elite schools.

The University of California, the California State University System and other public California campuses have banned legacy preferences for decades. But private colleges continued to give some preference to the descendants of alumni or major donors.

In a statement, Mr. Newsom said that “merit, skill and hard work” should determine college admissions. “The California Dream shouldn’t be accessible to just a lucky few,” he said, “which is why we’re opening the door to higher education wide enough for everyone, fairly.”

Schools with legacy preferences have argued that they have not compromised their high standards and that children of alumni who are admitted are highly qualified, or they would not have been accepted.

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