ST. PAUL, Minn. (AP) - A group of Minnesota parents and national education reform groups have filed a lawsuit challenging Minnesota tenure and dismissal laws that protect teachers.

The lawsuit was filed Thursday in Ramsey County. The Minnesota plaintiffs include four mothers from Duluth and the Twin Cities metro area.

At issue are laws that give layoff protection to teachers after three years on the job, require a lengthy procedure to fire them and set up a system where teachers with less seniority are fired first regardless of their performance.

The parents allege the laws are unconstitutional, perpetuate Minnesota's achievement gaps and prevent efforts to improve the state's public school system.

Education Commissioner Brenda Cassellius says Minnesota's laws protect teachers' due process while still giving school officials the authority to remove teachers.