A judge in Massachusetts has stopped President Trump's attempts to change how U.S. elections work. The judge agreed with Democratic state attorneys who said Trump's changes were against the Constitution. Trump's order, which came out in March, wanted people to show proof of citizenship to register to vote. It also said that mailed ballots would only count if received by Election Day, and states would only get federal election money if they followed this new rule. The White House said the order would 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 power over elections. The judge also stopped a part of the order that told states to reject any mail-in or absentee ballots received after Election Day. This is the second time a judge has blocked parts of Trump's election order, as a judge in Washington D.C. had already done this.