When liberals worry about losing a major Supreme Court case, they usually make appeals to the Court’s “legitimacy.” This is intended to attract Chief Justice John Roberts by suggesting that a conservative outcome would damage the institution’s reputation. The ritual is disingenuous but usually subtle.

Five Democratic Senators have had it with subtle. In a remarkable and threatening amicus brief, Sheldon Whitehouse, Mazie Hirono, Richard Blumenthal, Richard Durbin and Kirsten Gillibrand all but tell the Justices that they’ll retaliate politically if the Court doesn’t do what they say in a Second Amendment case.

“The Supreme Court is not well,” they tell the Justices in what is really an enemy-of-the-Court brief. “Perhaps the Court can heal itself before the public demands it be ‘restructured in order to reduce the influence of politics.’” By “restructured,” they mean packed with new Justices by a Democratic President and Senate after they kill the filibuster.

The case involves a challenge to a New York City law that banned licensed gun owners from bringing handguns outside the city even if a gun is unloaded and locked in a container separate from its ammunition. The Court accepted the case in January. Fearing a Supreme Court defeat, New York softened the restrictions and in July asked the Court to dismiss the case as moot. The Justices are scheduled to consider that question Oct. 1. The plaintiffs say the regulations are still unconstitutional.

The five progressive Senators are furious the Justices may rule on the case though the most constitutionally dubious provisions have been repealed. Their amicus brief claims the Court would be deciding a “hypothetical” issue. Their real fear is that the Court will clarify its Second Amendment jurisprudence and broaden protections for gun ownership.