Climate scientist Michael Mann argued in an interview posted Friday that Senate Democrats should face a litmus test requiring them to support expanding the Supreme Court.
He made the remarks on an episode of Stand Up! With Pete, hosted by Pete Dominick. Mann, who is a professor at the University of Pennsylvania, argued that Democrats retaking Congress would not be enough to advance climate regulation.
“When it comes to Senate races, there should be a litmus test,” Mann said. “It isn’t just good enough to be a Democrat. You’ve got to be a Democrat who would be willing to expand the Supreme Court.”
Mann told the host that voters concerned about the environment have one option in November.
“There is one party now that basically will do something about climate and one party that’s trying to undo all the progress,” Mann said. “There’s no way not to be partisan. There’s no way not to be political here. If you care about the environment, you’ve got to vote for the Democrats now.”
He tied the demand to a Supreme Court ruling on federal agency power, which he described incorrectly.
“It was in a conservative Supreme Court decision within the last few years that introduced the so-called Chevron standard,” Mann said. “Basically, what they said was that the EPA [Environmental Protection Agency] no longer had the authority to make rules based on the science and their own determination.”
The Supreme Court overturned Chevron deference in Loper Bright Enterprises v. Raimondo, decided 6-3 on June 28, 2024. The doctrine dates to 1984. Mann said on the recording that he could not recall whether the ruling came before or after the 2024 election.
Rep. Pramila Jayapal (D-WA) said in June that Democrat lawmakers were “absolutely” discussing expanding the Court from nine seats to 13.
House Minority Leader Hakeem Jeffries (D-NY) backed “dramatic reform” of the Court this month but declined to say if he supports adding justices.
WATCH — Hakeem Jeffries Calls Supreme Court “Illegitimate” After It Strikes Down Race-Based Voting Districts:
Two Democrats running for U.S. Senate, Texas state Rep. James Talarico and Iowa state Rep. Josh Turek, have called for ending life tenure without endorsing expansion, according to Bloomberg Law. Sen. Sheldon Whitehouse (D-RI) said in June that his position remains term limits.
Senate Judiciary Committee Chairman Chuck Grassley (R-IA) wrote in June that Democrats are pursuing the change because they cannot win at the ballot box.
“Since they can’t bulldoze their policies through the democratic process, they want to pack the court to ensure they never lose,” Grassley wrote. The number of justices has been fixed at nine since 1869.
Mann was sanctioned in March 2025 over evidence he presented at his own defamation trial against two bloggers. D.C. Superior Court Judge Alfred S. Irving ruled that Mann and his attorneys put erroneous grant-loss figures before the jury. Irving called the conduct “an affront to the Court’s authority.”
The jury had awarded Mann $1 million. Irving cut it to $5,000. Between that ruling and an earlier fee order, the scientist ended up owing those he sued more than $530,000.
“I am confident that neither I nor my lawyers did anything wrong during the trial,” Mann wrote on X.
