Thirteen state attorneys general sent a letter late last week to the nation’s largest employers warning them that they’ll “face serious legal consequences” if they use racial preferences in recruiting, hiring and contracting decisions.

The letter to Fortune 100 firms is the latest evidence that, while the U.S. Supreme Court’s decision last month striking down affirmative action in college admissions applies only to the education sector, it is emboldening critics of companies’ increasingly aggressive programs to bolster workplace diversity.