A state law requiring voters to show photo identification or swear to their identity is constitutional, the Michigan Supreme Court ruled Wednesday. The court's five Republicans voted to uphold the law while two Democrats dissented. The issue has fiercely divided Democrats and Republicans for a decade. The law was passed in 1996 and renewed in 2005, but it never took effect because former Attorney General Frank Kelley, a Democrat, ruled it violated the equal protection clause of the 14th Amendment, which guarantees citizens the right to vote.

Critics say the ID requirement is essentially a poll tax that would hit the poor, elderly, disabled and minorities hardest and keep them away from the polls. Supporters say it's needed to prevent election fraud.

The Michigan law requires voters to show photo ID to get a ballot, but it still allows those who don't have photo IDs to vote if they sign an affidavit swearing to their identity.

The high court's majority found Wednesday that the ID requirement isn't a poll tax because voters can choose to sign the affidavit instead.

Justice Robert Young Jr., in the majority opinion, said the ID requirement is a "reasonable, nondiscriminatory restriction designed to preserve the purity of elections and to prevent abuses of the electoral franchise."

Dissenting justices argued the state has no compelling interest in requiring ID because there is no evidence that in-person voter fraud exists in Michigan. Justice Marilyn Kelly said that "history will judge us harshly for joining those states that have limited the precious constitutional right to vote."

Several states have faced legal battles over laws requiring voters to show photo IDs. Judges have upheld voter ID laws in Arizona and Indiana but struck down Missouri's. Last month, the Georgia Supreme Court threw out a challenge to that state's voter ID law but sidestepped a decision on whether the requirement was constitutional.