In March 1954, the Senate formally confirmed Earl Warren as the new Chief Justice of the United States. One month later, a young lawyer in Arizona who’d recently clerked at the Supreme Court was already so incensed about Warren’s brief tenure that he wrote a letter to his former boss, Justice Robert Jackson, to complain about it.

“Most everyone here was quite disappointed by the nomination of Warren to the Chief Justiceship,” wrote William Rehnquist, who was then practicing at a law firm in Phoenix. Warren, Rehnquist continued, lacked the “experience” for the job, and did not possess sufficient “ability to think and write about law.” Furthermore, although Rehnquist told Jackson that he’d read only a “few” of Warren’s opinions, he said that they had “not been very good.” At the time, Warren had written all of four opinions, according to John A. Jenkins, author of the 2012 Rehnquist biography The Partisan; three of those opinions had been unanimous.

Most twentysomething lawyers in the elite circles in which Rehnquist ran would not so cavalierly dismiss the literal Chief Justice of the United States as an underqualified dunce, much less in a pontificating letter to one of his eight colleagues. (In The Partisan, Jenkins prefaces Rehnquist’s letter by diplomatically noting that Jackson never replied to it.) But in 1954, William Rehnquist was not most twentysomething lawyers. He was a budding conservative activist with elite credentials who was already brimming with contempt for anyone he viewed as intellectually inferior to him, and/or who sat even a little to his left on the ideological spectrum.

As Rehnquist became a bigger player in Republican politics, he continued to complain about Warren’s purported unworthiness to anyone who would listen. In remarks to a local GOP group in 1957, Rehnquist excoriated the members of the Court’s “left wing”—Warren, Justice William O. Douglas, and Justice Hugo Black—for “making the Constitution say what they wanted it to say.” He also called Warren a “fine California politician,” in the derogatory sense of the phrase, and claimed that Warren had been “58th out of 65 in his law school class.”