In the 2006 case of Helen Purcell, Maricopa County Recorder, et al. v. Maria M. Gonzalez et al., the U.S Supreme Court addressed a challenge to an Arizona law that required voters to present proof of citizenship when registering to vote and identification when casting a ballot in person. The plaintiffs argued that this law violated the Equal Protection Clause of the Fourteenth Amendment and was inconsistent with federal voting rights laws because it disproportionately affected minority, elderly, and low-income individuals who were less likely to possess necessary identification documents. However, after considering both sides' arguments, the court upheld Arizona's voter ID requirements as constitutional by refusing to block their enforcement for upcoming elections.

In the dissenting opinion for Helen Purcell, Maricopa County Recorder, et al. v. Maria M. Gonzalez et al., Justice Stevens argued that the majority's decision to uphold Arizona's voter identification law was premature and potentially harmful to eligible voters who may be disenfranchised by such requirements. He noted that while preventing voter fraud is a legitimate state interest, it should not supersede citizens' right to vote - particularly when there is no evidence of widespread in-person voter impersonation in Arizona or elsewhere in the country. Furthermore, he criticized the majority for making their ruling without sufficient factual record about how many people would be affected by this law and whether these individuals could easily obtain necessary identification documents.