The U.S. Supreme Court building in October 2015. (Jonathan Ernst/Reuters)
Opinion writer

For months now, Republican lawmakers have been asked what happens if President Trump fires special counsel Robert S. Mueller III or Deputy Attorney General Rod J. Rosenstein, and whether they will support legislation to protect either or both. The Senate Judiciary Committee, to its credit, passed out of committee a bill to give Mueller redress in court if fired without cause, to protect the investigation’s staff and documents and to report to Congress if the special counsel is fired. Senate Majority Leader Mitch McConnell (R-Ky.) keeps insisting he won’t bring it up, but then any member can try to introduce the bill by way of amendments to other measures. (As the Congressional Research Service says, “the rules impose a germaneness requirement only on amendments to general appropriations and budget measures and to matters being considered under cloture; various statutes impose such a requirement on a limited number of other bills. . . . In all other cases, Senators may propose whatever amendments they choose on whatever subjects to whatever bill the Senate is considering. The right to offer non-germane amendments is extraordinarily important because it permits Senators to present issues to the Senate for debate and decision, without regard to the judgments of the Senate’s committees or the scheduling decisions and preferences of its majority leader.”)

As important as that issue may be, an equally pressing concern should be the president’s possible refusal to provide an interview to the special counsel or to respond to a subpoena to testify to the grand jury in the Russia investigation. The White House is clearly laying the predicate for such action with White House spokesman Raj Shah falsely suggesting that the special counsel’s mandate is limited to collusion. In fact, the grant of authority explicitly states: “The Special Counsel is authorized to conduct the investigation confirmed by then-FBI Director James Comey in testimony before the House Permanent Select Committee on Intelligence on March 20, 2017, including: (i) any links and/or coordination bet ween the Russian government and individuals associated with the campaign of President Donald Trump; and (ii) any matters that arose or may arise directly from the investigation.”

The Supreme Court precedent is clear on whether Trump’s testimony can be compelled. Both in U.S. v. Nixon (telling Richard Nixon to turn over the tapes pursuant to a subpoena) and in the Paula Jones case (rejecting the argument that participation in a civil matter including a deposition “may impose an unacceptable burden on the President’s time and energy, and thereby impair the effective performance of his office”) the court held that the president is not beyond the reach of the normal discovery process in either criminal or civil matters. In Clinton v. Jones, the court found that “it is also settled that the President is subject to judicial process in appropriate circumstances. Although Thomas Jefferson apparently thought otherwise, Chief Justice Marshall, when presiding in the treason trial of Aaron Burr, ruled that a subpoena duces tecum could be directed to the President.”

Despite clear precedent, Trump may very well refuse to sit down with Mueller and then challenge a subpoena in court. Nothing is a slam dunk, but the chance that the courts would reverse the two seminal cases and exempt Trump from testimony is miniscule. Then what?

Here is where Congress should act with one voice. An appropriate simple, unanimous declaration from both chambers would state:

Pursuant to applicable Supreme Court precedent, the president must respond to a subpoena authorized by the special prosecutor pursuant to his grant of authority. Refusal to comply with a subpoena would be illegal and a material violation of the president’s oath of office to “take care that the laws be faithfully executed.” The president enjoys the same rights as any American under the Fifth Amendment to avoid self-incrimination. However, invocation of the Fifth Amendment to avoid cooperation with the special prosecutor shall be considered a material violation of the president’s oath and inconsistent with his obligations as the chief executive.

Simple enough. Each and every candidate for Senate and for the House should be quizzed as to whether he or she agrees with this articulation or whether they think presidents are entitled to avoid testifying under oath. It’s time to put aside specious arguments and get to the nub of the issue: Are presidents above the law? Any Republican who thinks so — or who thinks presidents can interpose their personal interests (by exercising their Fifth Amendment rights) to avoid complying with their oaths — has no business serving in office.

Here, the press should do its job and put the same question to GOP lawmakers: Will you allow Trump to avoid a subpoena? If Republicans want to head off a true constitutional crisis, they should emphatically answer in the negative.