BOSTON – On Friday, Democratic state attorneys general intend to challenge President Donald Trump’s extensive election reform plan in court. This case is significant because it touches on a fundamental constitutional principle—the separation of powers.

Law enforcement leaders from 19 states filed a federal lawsuit after the Republican president issued the executive order in March. They contend that the order infringes on state authority to establish their own election procedures and assert that the executive branch lacks this power.

Supporting their stance, a bipartisan collection of former secretaries of state argued that Trump’s directive disrupts the established system as outlined by the Constitution’s Elections Clause, which grants states and Congress the responsibility of managing elections. They claim the order attempts to “unilaterally position the President as the nation’s chief election policymaker and administrator.”

If the court does not halt the order, they argued, “the snowball of executive overreach will grow swiftly and exponentially.”

Trump’s election directive was part of a flurry of executive orders he has issued in the opening months of his second term, many of which have drawn swift legal challenges. It follows years of him falsely claiming that his loss to Democrat Joe Biden in the 2020 presidential election was due to widespread fraud and an election year in which he and other Republicans promoted the notion that large numbers of noncitizens threatened the integrity of U.S. elections. In fact, voting by noncitizens is rare and, when caught, can lead to felony charges and deportation.

Trump’s executive order would require voters to show proof of U.S. citizenship when registering to vote in federal elections, prohibit mail or absentee ballots from being counted if they are received after Election Day, set new rules for voting equipment and prohibit non-U.S. citizens from being able to donate in certain elections. It also would condition federal election grant funding on states adhering to the strict ballot deadline.

The hearing Friday in U.S. District Court in Boston comes in one of three lawsuits filed against the executive order. One is from Oregon and Washington, where elections are conducted almost entirely by mail and ballots received after Election Day are counted as long as they are postmarked by then.

The provision that would create a proof-of-citizenship requirement for federal elections already has been halted in a lawsuit filed by voting and civil rights groups and national Democratic organizations.

In that case, filed in federal court in the District of Columbia, the judge said the president’s attempt to use a federal agency to enact a proof-of-citizenship requirement for voting usurped the power of states and Congress, which at the time was considering legislation that would do just that. That bill, called the SAVE Act, passed the U.S. House but faces an uncertain future in the Senate.

Trump’s executive order said its intent was to ensure “free, fair and honest elections unmarred by fraud, errors, or suspicion.” The Justice Department, in arguing against the motion by the attorneys general for a preliminary injunction, said the president is within his rights to direct agencies to carry out federal voting laws.

The order tasks the U.S. Election Assistance Commission with updating the federal voter registration form to require people to submit documentation proving they are U.S. citizens. Similar provisions enacted previously in a handful of states have raised concerns about disenfranchising otherwise eligible voters who can’t readily access those documents. That includes married women, who would need both a birth certificate and a marriage license if they had changed their last name.

A state proof-of-citizenship law enacted in Kansas more than a decade ago blocked the registrations of 31,000 people later found to be eligible to vote.

The two sides will argue over whether the president has the authority to direct the election commission, which was created by Congress as an independent agency after the Florida ballot debacle during the 2000 presidential election.

In its filing, the Justice Department said Trump’s executive order falls within his authority to direct officials “to carry out their statutory duties,” adding that “the only potential voters it disenfranchises are noncitizens who are ineligible to vote anyway.”