Massachusetts joined 18 other states in a lawsuit against President Donald Trump’s March 25 executive order forcing the states to change their election procedures.

But the lawsuit — brought by the Democratic National Committee, the Democratic Governors Association, and Senate and House Democratic leaders over a recent executive order — argues that the order is unconstitutional, not for voting by noncitizens. Here’s a closer look at the facts.

The lawsuit, filed Thursday in federal court in Boston, seeks to have a judge block the provisions of Trump’s order and declare them “unconstitutional and void,” arguing that the order exceeds Trump’s authority and violates the separation of powers,