Timing of the filing in federal court Tuesday by the NAACP, American Civil Liberties Union and other rights groups coincided with the day three Michigan universities were granted a delay until 2007-08 in putting Proposal 2's mandates in effect for admissions and financial aid.
Wendell Anthony, president of the Detroit branch of the NAACP, said the group's appeal sought to have the extension made permanent, the Detroit Free Press reported.
"We have come too far to allow the doors of opportunity to be shut in the face of the American promise of liberty and justice," Anthony said.
However, the Center for Individual Rights in Washington also filed a challenge against the extension, spokesman Terence Pell said.
Pell said neither the parties to the suit nor the federal court have the authority "to second guess Michigan voters."
Michigan citizens who voted 58-42 percent in favor of Proposal 2, which bans race and gender-based preferences in university admissions and government hiring and contracting.