New Delhi, Nov. 4 -- Three Democratic justices on Pennsylvania's Supreme Court face retention votes this week in an unusually high-stakes ballot. Here's what the process means, how it works, and why it could affect future presidential contests.

In one of the most politically consequential state-level ballots in the United States, voters in Pennsylvania are deciding this Tuesday whether three State Supreme Court justices, all Democrats, will keep their seats. Normally a routine process, this year's retention election has drawn rare national attention - as control of the state's highest court in a key swing state could shape legal battles in the next presidential race.

The judges facing retention votes are Christine Donohue, Kevin M. Doug...