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 Trump's changes were against the Constitution. Trump's order, given in March, wanted people to show proof of citizenship to register to vote. It also aimed to only count mailed votes received by Election Day and to connect federal election money to states following these new rules. The White House said the order would make sure elections were "free, fair, and honest." However, 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 decision also stopped a part of the order that required states to reject any mailed votes 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 done so before.