Numbers are the first evidence of the sizable Thomas effect. He has had more of his former clerks nominated to federal judgeships under Trump than any other justice, past or present: 10, compared with Anthony Kennedy’s seven and Scalia’s five. Roughly one-fifth of Thomas’s former clerks either are in the Trump administration or have been nominated to the federal bench by the president. The clerks whom Thomas trained, has mentored, and actively stays in touch with are taking up lifetime appointments, and on the whole, they are quite young: Allison Jones Rushing, who now sits on the Fourth Circuit Court of Appeals, is just in her mid-30s.

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These relatively small numbers offer insight into the broad influence Thomas has had on the Trump-era legal establishment. Even clerks who aren’t in formal positions of public service have gained prominence under Trump: Laura Ingraham, the conservative commentator who clerked for Thomas during his early years on the bench, has hosted one of the top-rated programs on Fox News since October 2017 and is an outspoken supporter of the president. Another former clerk, Carrie Severino, the chief counsel and policy director of the Judicial Crisis Network, has been one of the most vocal advocates for Trump’s judicial nominees, including Kavanaugh.

The Thomas effect started taking shape early on in the Trump administration. As Slate’s Dahlia Lithwick and Mark Joseph Stern noted as early as mid-2017, when the pattern was still nascent, “Everywhere you turn in Trumpland, you’ll find a slew of Thomas’ former clerks in high places.” In part, this effect may have been driven by the people making the hires. Gregory Katsas, who clerked for Thomas on the D.C. Circuit and the Supreme Court, joined the Trump administration right after the inauguration as a deputy assistant to the president and deputy counsel. Later, when Katsas was nominated to his own judgeship on the D.C. Circuit Court, he told U.S. senators that he had been involved in “interviewing and recommending candidates for various executive and judicial appointments.” At least three other people who have worked in Trump’s White House counsel’s office are also former Thomas clerks: John Eisenberg, David Morrell, and Kate Todd. When the Trump administration released its list of potential Supreme Court nominees in November 2017, four former Thomas clerks were included: Thomas Lee, Margaret Ryan, David Stras, and Allison Eid.

Any new administration has a huge number of positions to fill across the executive branch. When Trump took office, he also faced significant judicial vacancies—142 empty seats, according to data from the American Bar Association. By comparison, when Barack Obama took office in 2008, there were only 53 federal judicial vacancies. These jobs are filled like any other: through personal networks and recommendations. Under Trump, the most influential source of potential candidates for these vacancies has been the Federalist Society, a professional network for conservative and libertarian lawyers. “It happens that a lot of the people in the White House counsel’s office are Federalist Society members, and as a result of having been Federalist Society members, they have their own set of contacts,” said John Malcolm, who works on judicial issues at the Heritage Foundation and is chairman of the Federalist Society’s criminal-law practice group. The organization’s executive vice president, Leonard Leo, has had an influential role in advising the Trump administration on possible nominees.