The high court's 6-3 decision rejected a challenge to a strict voter ID law in Indiana.
Democratic Representative Gwen Moore of Milwaukee says she thinks voter ID is a solution in search of a problem.
She says more use of voter ID policies will have the effect of keeping senior citizens, the poor, the disabled and minorities from exercising their right to vote.
Republicans in Wisconsin and across the nation have tried for years to require voter ID, claiming it's a good way to prevent voter fraud.
Democratic Governor Jim Doyle agrees with Moore that it would disenfranchise too many people. Doyle has vetoed voter ID bills three times since he took office in 2003.