While not a ruling on the merits of the executive order, the Court’s decision still overrules a series of federal court rulings blocking that order, which represents an unprecedented attempt by the Trump administration to seize control of election administration from the states, based on Trump’s demands for Republicans to “nationalize the voting” and “take over” the voting system.

It instructs the Department of Homeland Security to create lists of voters it deems citizens in each state, essentially overriding state voter rolls, and directs the Postal Service to only deliver mail-in ballots to voters on those lists, leading to the possibility that a significant number of voters will not receive mail-in ballots if the lists are inaccurate. (Trump, despite his frequent tirades against the practice, voted by mail in Florida’s primary last month, the second time this year he has done so in Florida.)