President Trump's executive order required the U.S. Postal Service to use state-by-state lists of eligible voters who may send a ballot by mail.

Lawyers for California and 22 other Democratic-led states sued, arguing that the states, not the federal government, have the constitutional authority to set the rules for voting and elections.

While Kennedy has refrained from commenting on the current court or President Trump, he has written a memoir that explains the reasoning behind the major decisions of his era.

The conservative justices see 'originalism' as a guiding principle to prevent judges from changing the Constitution to adjust to changing times. But that flipped this year.