Rosario v. Rockefeller
The Supreme Court saw a significant difference between the cases listed and the one before it. In each case, wrote Justice Stewart in the opinion, the Court had struck down statutes that made an entire group of people ineligible to vote, where there was nothing the people in that group could have done to become eligible. People who had not registered by a particular deadline, the Court asserted, did not constitute such a group, because they had it in their power to change their status. They were not absolutely disenfranchised by the deadline.
The remaining issue was simply whether the deadline presented "an unconstitutionally onerous burden" on the petitioners' exercise of their voting rights. While the deadline was indeed lengthy, the Supreme Court declared that it was not onerous, and that its length was justified by the necessity of preventing party raiding. "It is clear that the preservation of the integrity of the electoral process," wrote Stewart, "is a legitimate and valid state goal." New York's deadline for voting in primaries was an integral part of its scheme for achieving that goal; as such, it was constitutional.
Justices Douglas, Brennan, and Marshall joined Justice Powell, who wrote a dissenting opinion. New York's deadline, Powell wrote, was too severe. It prevented the voter from responding to a new issue or changing party philosophies. A less drastic deadline, he argued, would achieve the state's goal and allow the voter the full exercise of the voting rights so fundamental to democracy.