The Illinois Supreme Court on Thursday ruled 7-0 to allow Rahm Emanuel to run for mayor of Chicago.
The high court overturned a First District Appellate Court decision reached Jan. 24 that removed him from the ballot.
Justice Robert Thomas wrote that the lower court's ruling was "without any foundation in Illinois law."
A day after the appellate court ruled, the Justices put Emanuel, former White House chief of staff, back on the ballot and granted him leave to appeal the decision.
They ordered Chicago election commissioners to include his name on any ballots they print while the Supreme Court considers the case.
Emanuel moved to Washington in 2009, to work for President Barack Obama.
Last year he resigned and announced he would run for mayor in the Feb. 22 election.
Walter Maksym and Thomas McMahon of Chicago challenged his candidacy, arguing candidates must reside in the city for a year prior to the election.
Election commissioners ruled he belonged on the ballot, finding he never intended to terminate his Chicago residence or establish residence in Washington.
They applied an exception to residency requirements in state law for those who move away on business of the United States.
Cook County Circuit Judge Mark Ballard affirmed their decision, but First District Justices Thomas Hoffman and Shelvin Hall reversed Ballard on Jan. 24.
"We agree with the candidate that his service constituted business of the United States and thus that this exception applies to him," Hoffman wrote.
"We disagree, however, with his position that the exception saves his candidacy," he wrote.
Justice Bertina Lampkin dissented, writing that Hoffman and Hall disenfranchised Emanuel and everyone who would have voted for him.
For Emanuel, Michael Kasper of Chicago petitioned the Supreme Court a day later.
Kasper wrote, "Review of the ruling is essential to protect
Emanuel's right to ballot access, as well as to protect the right of the Chicago voters, 90,000 of whom signed his nominating petitions, to vote for him if they so choose."
He wrote that a person whose company assigns him to work in New York for a month would presumably fail the First District's standard.
"Years of litigation will be necessary to define this new standard," he wrote.
For Maksym and McMahon, Burton Odelson of Evergreen Park answered on the same date that Emanuel would disenfranchise voters.
"Although the right to vote is fundamental, the right to candidacy is far from a fundamental right," Odelson wrote.
"Petitioner narcissistically asks this Court to value his non fundamental right to be a candidate for mayor of the city of Chicago over the fundamental voting rights of potentially thousands of voters," he wrote.
He wrote that staying the First District decision would lead voters to believe Emanuel is a lawful candidate even though the First District held the opposite.
Ballots cast for him will be defective, resulting in disenfranchisement, he wrote.
"Tens of thousands of ballots may very likely be rendered meaningless through an unlawful candidacy," he wrote.
Steve Korris contributed to this report.