Atlantic Monthly has this commentary by a legal scholar, Garrett Epps, on why the 7th circuit decision Judge v Quinn is right to say that the U.S. Constitution requires a special election for Barack Obama’s old U.S. Senate seat on November 2, 2010.
As the column says, procedural problems with the lawsuit prevented the 7th circuit from ordering a special election; it is necessary for the U.S. District Court to take that action. For some reason the Epps column refers to the case as Judge v Backer, but the correct name of the case is Judge v Quinn. The decision came out on June 26, 2010.