It’s not every day that a member of one branch of the federal government tries to be the boss of the leader of a separate branch. But last week, a senior Senator on the powerful Judiciary Committee weighed in to claim that, instead of striving to uphold the Constitution, the Supreme Court should simply follow his branch’s lead.

“I trust that he will be a chief justice for all of us and that he has a strong institutional sense of the proper role of the judicial branch,” Senator Patrick Leahy (D–VT), said in a floor statement aimed at Chief Justice John Roberts. “The conservative activism of recent years has not been good for the Court. Given the ideological challenge to the Affordable Care Act and the extensive, supportive precedent, it would be extraordinary for the Supreme Court not to defer to Congress in this matter that so clearly affects interstate commerce.”

There’s a reason for Leahy’s 11-hour pressure campaign: During oral argument, several justices seemed to be leaning toward the idea that Congress doesn’t have the power under the Commerce Clause to force Americans to buy health insurance. As Heritage’s Hans von Spakovsky and Todd Gaziano explained on The Foundry:

There’s a difference between regulating commerce that’s already happening and forcing individual Americans to enter into commerce—in this case, the health care market—so that Congress can better regulate it. Justices Breyer and Sotomayor seemingly could not accept a meaningful difference between the two. If Congress were able to regulate things that people will eventually have to do, then there would be virtually no limits to its power.

And as Alexander Hamilton wrote in Federalist No. 78, judges must act to toss out unconstitutional laws, since “[n]o legislative act, therefore, contrary to the Constitution, can be valid.”

Leahy, in fact, is the one who seems to be violating precedent with his blatant attempt to influence a Supreme Court decision. Hamilton warned that while “the judiciary is beyond comparison the weakest of the three departments of power,” judges would be overstepping their bounds if they teamed up with members of the executive or legislative branches. In fact, he warned against actions such as Leahy’s, since the judiciary “is in continual jeopardy of being overpowered, awed, or influenced by its co-ordinate branches.”

It’s perfectly acceptable for a legislator such as Leahy to argue that the law is constitutional. Of course, many lawmakers couldn’t be bothered with making such arguments when they had the opportunity a few years ago. Recall that, when a reporter asked in 2009: “Where, specifically, does the Constitution grant Congress the authority to enact an individual health insurance mandate?” then-House Speaker Nancy Pelosi (D–CA) answered only, “Are you serious? Are you serious?”

Now it’s up to the Court to answer that serious question. Next month, it will.