When former President Trump’s second impeachment trial gets underway on Tuesday, the Senate proceedings will differ from what typically unfolds in a courtroom.
Court trials largely stick to a standard, uniform script. By contrast, the framers of the Constitution empowered the Senate to devise its own rules.
Historically, this has led to Senate trials diverging from courtroom protocol on issues like introducing evidence. The two venues also take vastly different approaches to punishment and the possibility of appeal.
Here are five big differences between court and Senate trials as lawmakers prepare to try Trump for his role in last month’s Capitol insurrection.
Senators are both judge and jury
In a courtroom, the judge and jury are two distinct entities. Jurors play a largely passive role — hearing evidence before rendering a verdict — while judges shape the trial’s contours by interpreting and applying rules and procedure.
In the Senate, however, 100 members play both roles, with at least 67 needed for conviction.
Under the Senate’s standing rules, it’s the lawmakers who have ultimate authority over all critical aspects of the proceeding.
“The senators have power over how the trial unfolds,” said Ian Ostrander, a political science professor at Michigan State University. “They are not passive jurors.”
There is no standard of proof
In both courtroom and Senate trials, the accusing party must prove their case. But the “burden of proof” concept is handled differently in a court.
Courtroom jurors are explicitly instructed by the judge as to the threshold that a plaintiff or prosecutor must meet to carry their burden of proof.
In a civil court case, the yardstick is a “preponderance of evidence.” In practice, this means a greater than 50 percent chance that an allegation has been proven. At criminal trials, the measure is raised to guilt “beyond a reasonable doubt.”
At Senate impeachment trials, however, no single uniform standard of proof exists. Instead, lawmakers are authorized to decide for themselves what burden the House impeachment managers must meet to successfully prove their case.
Given the Senate’s 50-50 partisan split, it’s unlikely in the current political climate that at least 67 senators will be persuaded to vote for Trump’s conviction.
That goal may prove even more elusive considering all but five GOP senators believe the upcoming trial is unconstitutional since Trump is no longer in office. It may be the case that no amount of proof could convince some senators to convict Trump if they think there’s no jurisdiction to try a former president.
There are no rules of evidence
Court trials follow a standard set of rules for handling evidence. There is some variability from state to state, but most courts share at least some common features with the federal rules of evidence.
Those standards guide judges on questions of evidence admissibility, relevance and whether an exception to the general bar on hearsay should apply.
But no equivalent set of rules exists for impeachment trials. Instead, each senator gets to use their own judgement on the facts and the law.
This issue came to a head in Trump’s first impeachment trial when the question arose of whether to call for live testimony from witnesses. Due to the lack of evidentiary rules, it fell to the senators to hash things out.
During a moment of heightened drama, then-Senate Minority Leader Charles Schumer (D-N.Y.) urged Supreme Court Chief Justice John Roberts, the trial’s presiding officer, to cast a tie-breaking vote in favor of allowing witnesses. Roberts declined, and no live witnesses were called.
“I think it would be inappropriate for me, an unelected official from a different branch of government, to assert the power to change that result so that the motion would succeed,” Roberts told Schumer.
Roberts will not preside over Trump’s second impeachment trial. Instead, Sen. Patrick Leahy (D-Vt.) will fill that role.
The punishment is political
When criminal defendants lose their case, they face the loss of liberty or property, and in jurisdictions that allow the death penalty, loss of life. In civil cases, the punishment usually takes the form of a defendant paying money to the plaintiff.
But just as an impeachment proceeding is political in nature, so is its final sanction.
Trump was a sitting president when he was tried for impeachment the first time, and conviction would have removed him from office. He was acquitted then, and is expected to be acquitted in his upcoming trial.
In the unlikely event that Trump is convicted, however, the Senate would then be expected to hold a second vote on whether to disqualify Trump from ever holding federal office again.
Impeachment verdict can’t be appealed
It’s common for the losing party in a legal proceeding to appeal to a higher court.
But impeachment has no mechanism for appeals. The Constitution gives the Senate the “sole” authority over impeachment trials.
Most scholars agree that in the context of an impeachment trial, the conduct of senators is not reviewable, meaning there’s no equivalent to the legal concept of jury misconduct.
The Constitution requires that senators swear an oath before the proceeding, and longstanding Senate rules on impeachment trials describe that oath as a promise to “do impartial justice.”
According to legal experts, the only available remedy against a senator who violates their oath would be to seek to expel a senator, or simply seek to have them voted out of office.