BOSTON, Aug. 13 -- When a federal appeals court in Washington cleared the way for President Trump's mail-in voting restrictions to resume across most of the United States in late July, election officials in dozens of states that had planned around court protections found themselves scrambling. The pause they had counted on was gone. The order requiring states to submit voter lists to the Postal Service and barcode every mail ballot before it could be delivered was active again, everywhere except the 23 states and the District of Columbia shielded by a separate injunction in Boston.

On Monday, that Boston court moved to shield the rest.

U.S. District Judge Indira Talwani expanded her preliminary injunction to all fifty states, blocking t...