In a 21-page opinion, federal judge Nancy G. Edmunds ruled that a portion of Michigan's primary election law is unconstitutional. Judge Edmunds agreed with the American Civil Liberties Union (ACLU) of Michigan and asserted that the state of Michigan cannot release voter party preference lists only to the Democratic and Republican Parties without violating the rights of minor parties, journalists, researchers, and the public. The ruling removed the portion of the law that made it a misdemeanor--punishable by up to 93-days in jail and a $1,000 fine--to provide the information to entities other than the two major parties.

However, while the judge in the case, the ACLU, and the State Elections Director have said that nothing in the ruling should impact the 2008 presidential campaign, Democratic Party chairman Mark Brewer said that without the voter preference information they would be unable to ensure that voters in a second primary or caucus had not also voted in the Republican Party primary in January.