U.S. appellate judge Merrick Garland pushed the Justice Department to the logical extremes of its defense of President Trump by getting a DOJ lawyer to say that Congress couldn’t sue if an administration on its own decided to pay for uninsured people’s health care.

The hypothetical came up in the oral arguments for two blockbuster cases in the ongoing war between Trump and the Democratic House. The cases were argued together Tuesday before the U.S. Court of Appeals for the D.C. Circuit.

Garland’s questions appeared particularly geared to the House’s lawsuit seeking to block the administration from using national emergency powers to pay for the border wall Congress refused to fund.

The Justice Department is arguing that Congress cannot use lawsuits to resolve spending disputes it has with the executive branch, an argument that a Trump-appointed district court judge previously backed.

On Tuesday, Garland laid out a hypothetical for DOJ lawyer Hashim Mooppan: Could a President, having failed to pass a health care reform bill, order the Treasury to pay for the health insurance of people who wanted coverage. The hypothetical appeared to be a sly reference to the push by progressives to expand Medicare to cover everyone. Republicans have railed against these legislative “Medicare for All” proposals. (Garland did not use that specific term.)

Mooppan said that Congress would not have the standing to bring such a case.

Garland’s line of inquiry also included a question about whether Congress could sue if a President funded a border wall if Congress explicitly forbade the President from doing so. Mooppan said no, while stressing that he was just answering a hypothetical.

Garland also posed a hypothetical wherein the administration unilaterally issued checks for Americans during the pandemic after a bill authorizing those checks failed in Congress. Mooppan said Congress could not sue in this case either, and the answer prompted a grilling from Garland on who would have standing in that scenario to sue to stop the administration from making those payments.

“That’s a significant power that the President has that can’t be checked by the Congress,” Garland said, referring to the power to spend on health or maintenance that his hypotheticals laid out.

Mooppan pushed back that Congress could check the executive branch by jamming the President’s legislative agenda or refusing to confirm nominees.

Doug Letter, the House General Counsel, also faced questions similar to Garland’s hypotheticals to Mooppan, about the kinds of scenarios in which the House would have standing to bring lawsuits if it disagreed with how the executive branch was implementing its laws. Letter argued that the appropriations clause of the Constitution distinguished congressional lawsuits challenging spending issues from other hypothetical types of congressional lawsuits against the executive branch, about which Letter expressed skepticism.

The border wall case was heard alongside the House Judiciary committee’s lawsuit seeking enforcement of its Don McGahn subpoena.

Because, in both cases, the Justice Department is arguing that the courts have no role to play in resolving the House’s claims against the administration, the cases stand to have major implications for the separation of powers and the system of checks and balances.

Judge Judith Rogers touched on the serious consequences if the courts ultimately agreed with the Department’s position.

“If, in a hypothetical situation, the President in his first year of office redoes the separation of powers … there’s nothing that can be done until the next presidential election, other than revolution,” she said.

The line, and particularly the invocation of “revolution,” prompted a testy response from Mooppan.

He said the implications of the border wall case were no more grave than previous cases that said that a President exceeded the statutory limits on his authority. And he argued that plaintiffs other than Congress could have standing under the Constitution to sue, including when it comes to challenging the border wall spending.

“That doesn’t mean we resort to revolution,” Mooppan said, while rattling off the other tools Congress would have available to push back on the President’s actions.

In addition to Garland’s hypotheticals pertaining to the border wall suit, the arguments in the McGahn case also prompted the Justice Department to take extreme positions to back its posture.

Judge Patricia Millett asked Mooppan if the House could ever go to court to enforce a subpoena of someone who was “indisputably” a private individual. The question appeared to be a reference to the DOJ argument that it was up to the executive branch to enforce subpoenas.

Mooppan said that, under the “broadest” formulation of the DOJ’s argument, Congress could not go to court to enforce a subpoena against a private individual.

“The power to sue to enforce the law is invested in the executive, not the legislature,” Mooppan said.

Letter, the House attorney, pushed back on Mooppan’s emphasis on the idea that Congress has tools other than lawsuits easily at its disposal if subpoenas are ignored. He brought up arguments that Trump’s lawyers made during the impeachment proceedings, where the House had alleged that the administration’s refusal to comply with subpoenas was obstruction of Congress.

“White House counsel told the Senate that the subpoenas could be ignored because, ‘The House should have gone to court to enforce the subpoenas,’” Letter recalled. “That is exactly, over and over again, what the President and his official government lawyers told the Senate of the United States: ‘Go to court and enforce those subpoena. And the President can ignore those subpoenas because you didn’t.’”

For more than a year, the House Judiciary Committee has been seeking the testimony of the former White House Counsel, who featured prominently in special counsel Robert Mueller’s report. The committee filed a lawsuit in July seeking a court order enforcing the April 2019 subpoena. A federal judge backed the House last fall, but her decision was reversed earlier this year in a 2-1 appeals court decision.

That decision, handed down by two GOP appointees, said that courts did not have the authority to resolve subpoena disputes between the executive and legislative branches, a stunning blow to Congress’ ability to perform government oversight — not just this administration, but administrations in the future.

Democratic-appointees make up a majority of the U.S. Court of Appeals for the D.C. Circuit, and Trump’s two appointees on the powerful court have both recused themselves from Tuesday’s arguments, presumably because of their previous roles in the administration. (Another GOP appointee is sitting for the border wall case only.)

It appears likely that the McGahn case will ultimately be decided by the Supreme Court, which has on its plate this term a House subpoena lawsuit seeking documents from Trump’s financial firms.