A federal judge in Detroit has rejected a challenge by the Michigan AFL-CIO to core provisions of Michigan's right-to-work law.

U.S. District Judge Stephen Murphy upheld the portion of the law that allows workers to not pay union dues as a condition of employment.

In his ruling, Murphy says that right-to-work laws (quote) "are a valid exercise of state regulatory power."

However, Judge Murphy did allow other parts of the union's lawsuit to continue. The Michigan AFL-CIO filed a lawsuit against the state soon after the right-to-work law took effect in March 2013.

The union argues the state law violates the U.S. Constitution because private-sector unions are covered by federal law and governed by the National Labor Relations Board, not state law.

AFL-CIO attorney Andrew Nickelhoff says (quote) "significant parts of our case are going to go forward, so I think that’s a significant victory." Attorney General Bill Schuette calls the decision a great victory for workers.