RICHMOND, Va. — On the night Barack Obama became the nation’s first black president, Leah Taylor, a fast-food worker and African-American mother of six, stayed up until 2 a.m. watching the election returns. “I knew that was history, and I wanted to be a part of it,” she said. But she did not vote.

Ms. Taylor, 45, has never voted. In 1991, when she was 20, she was stripped of her voting rights after being convicted of selling crack cocaine and sent to jail for a year. So she was stunned when an organizer from a progressive group, New Virginia Majority, showed up one recent afternoon at the church soup kitchen where she eats lunch and said he could register her.

“Your rights have been restored!” the organizer, Assadique Abdul-Rahman, declared with a theatrical flourish, waving an executive order signed in April by Gov. Terry McAuliffe. Ms. Taylor, so moved she nearly cried, promptly signed up.

Thus did Ms. Taylor join a wave of newly eligible voters, all with criminal pasts, signing up in Virginia. But what Mr. McAuliffe granted, the Virginia Supreme Court may now take away.