The reasonable person standard is an artful fiction devised by the American legal system to help a trier of fact (almost always a jury) determine whether a defendant acted negligently. The clearest definition I’ve found for reasonable person is someone who “exercises average care, skill, and judgment in conduct that society requires of its members for the protection of their own and of others’ interests.”

In other words, not an expert, but someone committed to reason and the general good. If the defendant acted in a manner consistent with a reasonable person, the trier of fact should exonerate. If the defendant acted in a manner inconsistent with a reasonable person, the trier of fact should impose liability.

Soon the members of the United States Senate will serve as triers of fact in an impeachment trial. The Constitution sets impeachment trials apart from other legal proceedings. For instance, there is no specified standard of proof (normally “beyond a reasonable doubt” in criminal cases and “by a preponderance of evidence” in civil cases). Nor does the jury have to be unanimous; a two-thirds majority of the Senate secures conviction.

So evaluating the president’s actions through the reasonable person standard isn’t required. But in my opinion it should be, because it emphasizes reason and a commitment to the public good — just what’s needed to head off charges the trial will be a partisan exercise.

But here’s the problem: if the Republicans follow the reasonable person standard, they will have to convict their Republican president.

Hundreds of Constitutional scholars agree Trump committed impeachable offenses in his dealings with Ukrainian president Zelensky. Even Jonathan Turley, the Republicans’ chosen Constitutional expert, acknowledges this: “The use of military aid for a quid pro quo to investigate one’s political opponent, if proven, can be an impeachable offense,” he told the House Judiciary Committee. American presidents just don’t do that — not reasonable ones, anyway.

So then it becomes a matter of sufficient proof. Again, there is no standard. Turley bases his defense of Trump on a peculiar, perfect-versus-good standard: unless you’ve heard from all witnesses you can’t establish guilt, and unless the legal process has fully played out you can’t interpret the Administration’s refusal to cooperate in the investigation as obstruction of justice.

Except you can! Because Turley’s perfect-versus-good standard is pure invention. (One with nowhere near the reasonable person standard’s usefulness or pedigree.)

That said, I would expect a reasonable person to examine all the available evidence before coming to conclusions. In this case, it’s not even close: there is ample direct evidence that Trump put his political interests ahead of the nation’s with regard to Ukraine, and no evidence to the contrary. One could argue that Administration officials who have refused to testify would provide contrary evidence if compelled to appear, but that argument is belied by the extraordinary steps Administration personnel took to hide the July 25 call between Trump and Zelensky. The inner circle knew right away something incriminating happened in that exchange.

Another counter-argument is that there can’t be a high crime or misdemeanor because Ukraine didn’t investigate the Bidens and got its foreign aid. But in contrast to schoolyard basketball, in American jurisprudence “no harm, no foul” is not a concept. Attempting a crime is still a crime, regardless of outcome.

So in the end, I don’t see how a reasonable person reviews the evidence, hears the expert testimony (including that of the defendant’s own Constitutional law professor), and fails to conclude there’s sufficient proof the president of the United States engaged in impeachable conduct.

Well, I suppose there is one way. You could redefine the reasonable person standard. You could dumb down “average care, skill, and judgment” to mean “openness to unproven conspiracy theories” and “protection of their own and of others’ interests” to “protection of their own political party.”

Which is pretty much what we’re seeing from the Republicans.

Let’s not tolerate false equivalences. The impeachment trial may devolve into a partisan exercise, but almost all the partisanship will come from the Republicans. The Democrats, despite the ill will they may harbor toward Trump, have stuck doggedly to the reasonable person standard since launching the impeachment inquiry.

Assuming the reasonable majority eventually wins this struggle with authoritarianism, the stunning irrationality of Trump’s defenders will be virtually undisputed twenty or thirty years from now.

South Carolina senator Lindsey Graham. Boy is this guy’s career gonna be hard to explain in 30 years.

Former Risk Manager at UC Berkeley, author of four books, ectomorphic introvert.