U.S. House Judiciary Committee members Steve Chabot, Doug Collins, Louie Gohmert and Jim Jordan discuss articles of impeachment against President Donald Trump on Dec. 12, 2019. The articles were rejected by the Senate on Feb. 5, 2020. Photo: Diego M. Radzinschi/ALM

Following the U.S. Senate's failed impeachment vote, lawmakers must establish a standard of proof required for all impeachment proceedings. Right now there is none, and senators, lawyers and nonlawyers alike deserve an established lens through which to view the evidence presented.

Standards of required proof are widely understood by the public at large, from the criminal "beyond a reasonable doubt" to the "clearly wrong" review of a referee's call during an NFL game.

Most arbitrators either apply a "preponderance of the evidence" standard for discharge of an employee or "clear and convincing evidence" when the employee's conduct involves criminal charges or charges which upheld would bring the employee into serious disrepute.

The Constitution provides no guidance on the question. Article 1, Section 3, clauses 5 and 6 simply state:

The Senate shall have the Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation. When the President of the United States is tried the Chief Justice shall preside: and no Person shall be convicted without the Concurrence of two thirds of the Members present. Judgement in Cases of Impeachment shall not extend further than removal from Office, and the disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law. 

There have been attempts in the past to establish a standard. In the Senate impeachment trial of U.S. District Judge Harry E. Claiborne, the defendant argued that a "beyond a reasonable doubt" standard should apply. The House manager argued that since criminal sanctions could not be imposed, a criminal standard of proof was not required.

In the impeachment case of President Richard Nixon, the House Judiciary Committee minority argued that "beyond a reasonable doubt" was the appropriate standard.

At the initial meeting of the Senate Impeachment Trial Committee for consideration of articles of impeachment against Judge Alcee Hastings, Sen. Joseph Lieberman asked for guidance on the "threshold the evidence has to cross for us to make a judgment of guilt or innocence against this judge." Sen. Warren Rudman replied: "I don't think you are going to find one, Joe. I think it is going to be whatever you apply to it. … It is what is in the mind of every senator. If you want to use clear and convincing, preponderance, if you what to use beyond a reasonable doubt—I think it is what everybody decides for themselves."

U.S. senators deserve better guidance on such momentous decisions, despite the political nature of many of them. The public deserves better. After the next election, the Senate should establish a bipartisan committee to formulate a Senate resolution to establish a standard of proof as guidance in future impeachment proceedings.