Nevada's largest teachers union has filed a lawsuit challenging a state law that makes it illegal for public school employees including teachers to go on strike.

Nevada’s largest teachers union filed suit Monday against a state law making it illegal for teachers and other public school employees to go on strike over pay and working conditions in the country’s fifth-largest school district, which includes Las Vegas.

The Clark County Education Association argues in its lawsuit that the 1969 state law prohibiting public employee strikes is unconstitutional. They said it also infringes on the First Amendment rights of its approximately 18,000 members in nearly 380 schools in Las Vegas and surrounding Clark County who are waging a contentious monthslong contract battle.

They also argue that the state’s definition of a strike is overbroad, sweeps away constitutional rights and gives way for arbitrary and discriminatory enforcement.