JONATHAN TURLEY: University of Pennsylvania professor calls for litmus test for all Democratic candidates

University of Pennsylvania Professor Urges Democratic Candidates to Commit to Supreme Court Expansion

Philadelphia, Pa. — In a recent interview on a public‑radio podcast, University of Pennsylvania climate science professor and vice provost for Climate Science, Policy, and Action Michael Mann called for a “litmus test” for Democratic candidates. According to Mann, any Democrat who wants to run must pledge to expand the U.S. Supreme Court, a move he says is essential to pass climate‑related reforms.

Mann, who has been a prominent voice in the climate science community for more than two decades, said the Court’s current composition has become a barrier to ambitious environmental legislation. “If you care about the environment, you’ve got to vote for Democrats who are willing to expand the Court,” he told the podcast host. “There’s no way not to be political here.” The professor’s comments have drawn attention from a range of political commentators and party insiders.

The call to expand the Court is not Mann’s first public statement about the institution. The Supreme Court’s 2024 ruling in Loper Bright Enterprises, Inc. v. Raimondo overturned the “Chevron” deference doctrine, a decision Mann mistakenly cited in a previous lecture as having removed agency authority over climate regulation. In fact, the 2024 ruling clarified that courts will now review agency decisions more closely, but it did not strip agencies of the power to set rules based on scientific evidence.

Mann’s advocacy for Court expansion sits alongside a broader movement within some Democratic circles. Former Vice President Kamala Harris and former Transportation Secretary Pete Buttigieg have publicly called for enlarging the Court, while Senator Elizabeth Warren has renewed her longstanding push for a “court‑packing” plan. In contrast, political strategist James Carville has urged Democratic leaders to keep such moves out of the public eye.

The professor’s recent legal troubles may also be relevant to his political messaging. In 2025, Mann was sanctioned after a defamation lawsuit involving bloggers Rand Simberg and Mark Steyn. The case ended with Mann and his legal team required to pay $1.1 million in legal fees to the plaintiffs, after a court found that his lawyers had presented false financial figures during the trial.

The Supreme Court’s composition has long been a point of contention in American politics. Since the 1930s, presidents have attempted to appoint additional justices to shift the ideological balance of the Court. The idea of expanding the Court to 15 seats, often referred to as “court‑packing,” has been proposed by various politicians across the political spectrum, although it has never been enacted.

Political analysts note that calls for expanding the Court are part of a broader debate about the role of the judiciary in shaping policy. Some argue that a larger Court could facilitate the passage of climate legislation and other progressive initiatives. Others caution that a more partisan Court could erode public confidence in the judiciary’s independence.

Mann’s remarks come at a time when the Democratic Party is gearing up for a crowded slate of Senate and House races in the next election cycle. While no official policy has been adopted to require candidates to pledge support for Court expansion, the conversation is gaining traction within some progressive circles.

Whether or not a “litmus test” for Supreme Court expansion becomes a reality remains to be seen. Nonetheless, the debate illustrates the deepening partisan divide over the nation’s most powerful judicial body and the extent to which it should be used as a tool for advancing policy agendas.