Alan Dershowitz’s greatest impact on American law likely came at the beginning of his career. In 1963, Justice Arthur Goldberg tasked him to help build an argument against what had, until then, gone unquestioned: the constitutionality of capital punishment. Dershowitz—then a young Supreme Court clerk, now a Harvard University law professor emeritus—compiled some of the earliest statistics on racial disparities in the death penalty. Every case he found in which a rapist had been sentenced to death, for example, involved a black defendant and a white victim.

Goldberg’s eventual dissent in a death-penalty petition did not include this research. According to legal historian Evan Mandery, who wrote a 2013 book about the initial campaign to abolish the death penalty, the other justices pressured Goldberg to omit these findings from his dissent, partly because they would inflame the South. He assented but subsequently told Dershowitz that he was free to do whatever he wanted with his underlying research. He promptly sent copies of it to the ACLU, the NAACP Legal Defense Fund, and similar organizations. Death-penalty abolitionists have highlighted racial disparities in executions ever since.

Over the next few weeks, Dershowitz will likely make his second-greatest contribution to American law. The White House announced last week that he will be joining President Donald Trump’s legal team for his impeachment trial. Dershowitz said that he will address the Senate to discuss his constitutional theory on the matter. The imagery may be more important than the substance: Trump will have a famed liberal lawyer, one who voted for Hillary Clinton in 2016 and endorsed Joe Biden in 2020, telling senators that it would be unconstitutional to punish the president for his scheme to coerce a foreign power into falsely smearing one of his political rivals.

The American legal community has spent the Trump era wondering aloud what happened to Alan Dershowitz. He told me in 2018 that he hadn’t actually changed; it was everyone else who was different. There’s a certain truth to this. Dershowitz’s career is a testament to the effects that celebrity, affluence, and fame can have on even the most formidable legal minds. His client in the Senate trial won’t be Trump, or even the presidency as an institution, but power itself.

Dershowitz, like Trump, also has an ineluctable power to draw media attention.

Dershowitz, like Trump, also has an ineluctable power to draw media attention. “I’ve discovered that the most dangerous place to be in the criminal justice system is not the Federal Penitentiary at Marion or the holding cell at the Tombs, but between Alan Dershowitz and a television camera,” Brian Wice, a Texas lawyer who worked alongside him in the Jim and Tammy Faye Bakker case, quipped in 1991. Dershowitz’s ubiquitous appearances on television made him perhaps the best-known living American lawyer in the 1980s and 1990s. One book reviewer, writing about O.J. Simpson lawyer Robert Shapiro’s account of the TV-driven case in 1996, wondered if Shapiro had hired Dershowitz “mainly to shut him up.”