Colorado's largest teachers union is challenging the firings of about 100 Denver teachers and a 2010 law that enabled the dismissals.
The Colorado Education Association says the law is flawed because it allows administrators to approve or deny the transfer of a teacher to their school. The lawsuit filed Wednesday argues that about 100 Denver teachers have been placed on unpaid leave even though they are experienced teachers with good evaluations.
The Democratic sponsor of the law says it's an important modernization for the profession. Republicans also criticized the lawsuit.
The CEA says it does not oppose the new teacher tenure provisions in the law. That's a statewide teacher-grading system that sorts educators from "highly effective" to "ineffective."
The effectiveness ratings began for all 178 Colorado school districts this fall.