By empowering county registrars to "reject any application for registration that is not accompanied by satisfactory evidence of United States citizenship," the "proof of citizenship" provision of Proposition 200 resulted in a disproportionately high number of voter registration rejections for Latino, other minority, and poor applicants, thereby discriminating against (to say nothing of discouraging) potential low income and/or non-white voters. Even worse, the purported goal of the statute — to curtail voting by illegal immigrants — was belied by the fact that "Arizona failed to identify a single instance in which an undocumented immigrant registered or voted in the state."
Finally, for those who were unmoved by the disturbing spectacle of a state using a non-issue as an excuse to practice racial and socioeconomic disenfranchisement, there was the simple reality of the measure's unconstitutionality. As Justice Antonin Scalia pointed out when writing for the court's 7-2 majority, Congress is clearly vested with the power to establish the “times, places and manner of holding elections.” Because federal registration forms (and consequently their state equivalents) only require prospective voters to state by oath that they are American citizens, under penalty of perjury, Arizona went beyond the proper scope of its powers by requiring naturalization documents.
At the same time, it is important to remember that Proposition 200 was only a single battle in a larger war.
As demographic trends are making clear, non-white voters are rapidly increasing both in sheer numerical size and in their overall share of the American electorate. While this may not have posed a problem for the pre-1964 GOP, the nomination of Barry Goldwater that year, the so-called "Southern Strategy" used by Richard Nixon in the next two elections, and the racial politics employed by Ronald Reagan have all resulted in an intense aversion among minorities toward the Republican brand. Although the seemingly logical solution would be to find meaningful ways of reaching out to non-white voters, much of the conservative base remains wedded to coded racist policies, from opposition to welfare (which, despite popular misconception, has been proved to neither disproportionately benefits minorities nor exist primarily as a crutch for those who could work but simply choose not to) to prejudice-based desires to restrict Latino immigration (as embodied by the claim of the co-author of an influential Heritage Foundation study that Hispanic immigrants are less intelligent than white Americans). Indeed, even as I write this, a proposed bipartisan immigration reform measure is being stymied in Congress by severe right-wing backlash.
With racial progressivism thus ruled out, Republicans are left with only two options.
The first is to nominate as many non-white political candidates as possible for high profile offices, in the hope that ethnic identification will siphon off minority voters (whether this would work remains to be definitively determined).
Barring that, or perhaps even alongside it, is the plan to simply prevent non-whites from voting.
That is why 19 states have passed laws and executive actions intended to hinder non-white voting since 2011 (most of which, like the Proposition 200 clause, are based on entirely groundless claims of voter fraud). It is why the Supreme Court is scheduled to issue a decision on whether to overturn key provisions of the Voting Rights Act of 1965, which laid the foundations for the voting protections offered to minorities today. It explains why the Supreme Court conservatives who sided against Arizona encouraged the state to find other means of accomplishing its goal, such as asking the federal government to include state-specific instructions on its form and taking it to court if it refuses. Finally, it explains why a major backlash from the right-wing against the Supreme Court's recent decision is inevitable, and how even though none of the critics will dare acknowledge that they are motivated by a desire to suppress non-white voting, they will nevertheless continue to find a plethora of bugaboos to prop up and find creative new methods of fighting them that just so happen to hinder minority voting.
While it is tempting to herald Monday's victory as a blow against legalized racism, as a matter of fact it is little more than a thumb plugged into just one of the cracks in the dike of electoral oppression. It may be too early to say who will ultimately win this war for America's soul, but there can be little doubt that we have only heard the opening salvos.