BOSTON — A trial is set to begin in a lawsuit challenging the constitutionality of a Massachusetts law that requires voters to register at least 20 days before an election.

The American Civil Liberties Union of Massachusetts, along with the national ACLU Voting Rights Project and a Boston law firm, filed the lawsuit in November.

The lawsuit asks the court to declare the law unconstitutional and to order the government to end enforcement of the law.

The ACLU says the registration cutoff law arbitrarily disenfranchises thousands of potential voters in Massachusetts.

The trial is scheduled to begin Wednesday in Suffolk Superior Court.