A judge in Massachusetts has stopped President Trump's plan to change how U.S. elections work. This decision supports a group of Democratic state lawyers who said his actions were against the Constitution. Trump's order, which he issued in March, wanted to make people show proof of citizenship to register to vote. It also wanted to only count mailed votes received by Election Day and connect federal election money to states following these new rules. The White House said the order was to make sure elections were "free, fair, and honest." But Judge Denise J. Casper decided that the states would probably win their legal cases. She explained that the Constitution does not give the President special powers over elections. The judge's decision also stopped a part of the order that told states to reject any mail-in or absentee votes received after Election Day. This is the second time Trump's election order has had legal problems, because a judge in Washington D.C. had already stopped parts of it.