Operation Eagle Eye was a Republican Partyvoter suppression operation in the 1960s in Arizona to challenge minority voters. In the United States only citizens have ever been able to vote, and in 1964 only literate citizens could vote, so it was legal to ensure that (1) a potential voter was literate, and (2) a potential voter was a United States Citizen. Through the employment of literacy tests, oral demands to interpret the United States Constitution and detailed questions about a potential voter's origins and how long the potential voter had been in the United States, Republican workers would challenge minority voters, especially those with broken English. William Rehnquist, later chief justice of the Supreme Court of the United States, is said to have been the head of a group of lawyers hoping to challenge voters in minority Democratic precincts. Operation Eagle Eye was a two-year effort, and the laws in Arizona have since made this kind of challenge illegal.