Are the Republican senators who voted to dismiss the impeachment charges against Donald Trump now required — since they interpret the Constitution as barring a trial — to find him not guilty? Or are they free — at least in theory — to vote to convict the former president?

This week, 44 senators — all members of the GOP — said they were persuaded by Trump’s argument that it’s unconstitutional to try him because he is no longer in office. But they were overruled by all 50 Democrats, plus six Republicans, who found that the trial should proceed. Under the established Senate procedure, the jurisdiction issue was to be resolved by majority vote, with all senators then expected to adhere to the result.

So the responsibility to proceed with the trial should be clear — especially for members of a party that purports to stand up for law and order.

Traditional legal principles support not only the idea that these senators are empowered to vote for conviction, but also that they should. Indeed, respecting the agreed-upon process and then holding Trump accountable would be the more conservative approach.

Of course, the argument that the Senate lacks jurisdiction over a departed president may be a dodge on the part of Republican senators desperately seeking an escape hatch to avoid passing judgment on Trump. Still, while the majority of legal scholars believe the Constitution allows an impeachment trial of a president who is no longer in office, there is at least an arguable case to the contrary.

So let’s assume, for the purposes of this column, that Republican senators who voted to dismiss the charges were acting in good faith. How should they now proceed? Senate Minority Leader Mitch McConnell (R-Ky.) has stated his understanding that senators who, like him, personally believe the Senate lacks jurisdiction can still vote to convict Trump, but other Republicans disagree.

There is an extensive body of law on how jurors and judges should respond when they disagree with law they are asked to apply. This precedent is instructive, even with the understanding that the impeachment process is quite different from ordinary legal proceedings.

In every impeachment, senators are called on to act as both judges and jurors — they both determine what the law is and decide how to apply it to the facts at hand.

Our legal system sets out different rules and roles for jurors and judges. Basically, jurors are expected to follow the law — even when they don’t agree with it. However, a practice called “jury nullification” allows them to find a criminal defendant not guilty when the jurors think the person committed the crime but view the prosecution as unfair. In most jurisdictions, jury nullification is discouraged, but the Supreme Court has ruled that it’s a constitutional prerogative of jurors.

Thinking about the senators as jurors, assume there are Republican senators who believe Trump actually incited the insurrection but voted against proceeding with the trial. These senators would be engaging in the Senate version of jury nullification if they disregarded the majority’s interpretation of the Constitution and voted to acquit.

Considering senators in their role as judges points to a more constrained role. Generally, judges are supposed to apply the existing law whether they like it or not, or even if they believe the prevailing view of the law is wrong or even unconstitutional. This issue has come up in Supreme Court death penalty cases, in response to the court’s 1976 ruling upholding capital punishment.

Two justices, Thurgood Marshall and William J. Brennan Jr., dissented in that case, and subsequently refused to consider any future death penalty cases on the merits. Because their view was that the very practice is unconstitutional, they automatically voted to overturn every death sentence that came before the court, even when the law had been correctly followed.

Justice John Paul Stevens took a different approach. Stevens came to agree with Marshall and Brennan that the death penalty was unconstitutional, but he accepted that the court’s majority had ruled to the contrary. Thus, Stevens voted on occasion to uphold death sentences that he thought were consistent with the law — even law that he personally believed was unconstitutional.

So Senate Republicans who vote to acquit Trump on the grounds that he is no longer subject to impeachment would be acting in the proud tradition of nullifying jurors and iconic liberal justices. Cool, but hardly conservative.

Many years ago I wrote a scholarly article describing my experience with jury nullification as a prosecutor in D.C. Frequently, in nonviolent drug cases, African American jurors would nullify. They would explain they knew the guy was guilty, but they didn’t want to send another Black man to jail. When, as a scholar, I endorsed this practice, I caught hell from conservatives who claimed that nullification undermined democracy and the rule of law.

If their conservative principles actually matter, Republican senators should play by the rules. That means considering the case on the merits, and voting to convict.

Read more: