A civil plaintiff has to prove his case by a preponderance of the evidence; a prosecutor has to prove hers beyond a reasonable doubt. We all learned these rules in law school, but I did not truly appreciate why they exist until, as a new trial judge, I was confronted with the testimony of two equally believable witnesses, one saying the light was green and the other saying it was red. As I agonized with a colleague over what to do, he replied, "Who has the burden of proof? Whoever they are, they lose."
That was when it hit me: Burdens of proof are, at bottom, jurisprudential tie-breakers. They tell a trier of fact harboring some uncertainty how to decide the case. Burdens of proof necessarily have two components: (1) who bears the burden, and (2) what the burden is (a preponderance of the evidence, clear and convincing evidence, or beyond a reasonable doubt). If we view a burden of proof as telling us, "The tie goes to 'X'", then "X" is the party not bearing the burden of proof, and a "tie" exists when the trier of fact is unsure if the applicable burden has been met.
Burdens of proof are presented in law school as if they are well-settled and purely procedural. In actuality, they are neither.
They are not purely procedural.
Burdens of proof are assigned and defined both by legislative bodies and courts. In civil cases, the default rule is that the plaintiff bears the burden of proving his case by a preponderance of the evidence. Colorado v. New Mexico, 467 U.S. 310, 316 (1984); Cal. Evidence Code, section 115. That is because the civil plaintiff is seeking to alter his relationship with the civil defendant by obtaining a judgment against her, so inertia dictates that any uncertainty favor the status quo. And civil cases involve property (be it real or personal), so proof by a preponderance is sufficient to protect the civil defendant.
In criminal cases, the federal Constitution mandates that the prosecutor prove the defendant's guilt beyond a reasonable doubt. In re Winship, 397 U.S. 358, 362 (1970). Proof by a preponderance of the evidence will not do, the Supreme Court has held, because a verdict in a criminal case takes away the defendant's reputation and, in many cases, his liberty. This highest of burdens of proof is also "critical" to the public's perception that the criminal justice system is legitimate: "[T]he moral force of the criminal law" must "not be diluted by a standard of proof that leaves people in doubt whether innocent men are being condemned."
In between these two poles, the legislatures and courts have in some non-criminal cases dictated that litigants must prove their cases by the Jan Brady of burdens of proof, clear and convincing evidence. This intermediate burden of proof is typically reserved for situations in which more is at stake than money or property, such as parental rights, Santosky v. Kramer, 455 U.S. 745, 748 (1982), freedom from involuntary commitment due to mental illness, Addington v. Texas, 441 U.S. 418, 433 (1979), or ability to remain in the country, Woodby v. INS, 385 U.S. 276, 285-86 (1966).
Each of these burdens of proof requires the party with the burden to present evidence, but legislatures can lighten that evidentiary burden with presumptions. Presumptions are evidentiary shortcuts. Instead of having to prove "fact B," a presumption allows the plaintiff instead to prove "fact A," which is typically easier to prove and from which the trier of fact may (or, at times, must) infer "fact B" to be proven. Presumptions run the gamut of topics -- from the presumption of death from five years of non-communication, Cal. Evidence Code section 667, to the presumption of negligence under the doctrine of res ipsa loquitur, id. section 646. Presumptions generally come in three flavors: (1) permissive inferences allow (but do not require) the trier of fact to infer fact B from fact A, (2) rebuttable presumptions require the trier of fact to infer fact B from fact A, but allow the other party to rebut that inference, and (3) conclusive presumptions are non-rebuttable. Because the last two types of presumption effectively shift -- and thereby lighten -- the burden of proof, they are not permitted in criminal cases. Sandstrom v. Montana, 442 U.S. 510, 523-24 (1979).
Although burdens of proof and presumptions bear the earmarks of being wholly procedural, they implement substantive public policy. This is undoubtedly why, in federal diversity cases, presumptions are considered "substantive" for purposes of Erie Railroad Co. v. Tompkins, 304 U.S. 64 (1938). See Fed. Rule of Evidence 302.
Burdens of proof are also not as well settled as one might believe.
There has been a fair bit of movement in the last few decades -- and in the past few years -- on how burdens of proof are to work in court proceedings. As noted above, legislatures and courts share the task of defining burdens of proof, but courts are still trying to decide where to draw the line delineating their respective spheres of authority. It is only in the last 40 years that that the United States Supreme Court ruled that legislatures cannot call a bona fide element of a crime an affirmative defense (and thereby require the defendant to disprove it), Patterson v. New York, 432 U.S. 197, 210 (1977), and in the last 20 years that the court ruled that legislatures cannot call facts affecting a defendant's sentence "sentencing factors" (and thereby allow a court to find them by a preponderance of the evidence), Apprendi v. New Jersey, 530 U.S. 466, 490 (2000). It was not until last year that the California Supreme Court ruled that courts trying to reconstruct the elements of a prior conviction could not look beyond what the prior jury found or what the defendant admitted during the prior plea. People v. Gallardo, 4 Cal. 5th 120 (2017). And it was not until earlier this year that the California courts for the first time invoked the federal Constitution to set a new minimum burden of proof of clear and convincing evidence for denying bail in criminal cases. In re Humphrey, 19 Cal. App. 5th 1006, 1037 (2018).
Even though burdens of proof are generally a topic that only a lawyer could love, it is a topic that hit the prime time after Dr. Christine Blasey Ford accused Circuit Judge and U.S. Supreme Court nominee Brett Kavanaugh of sexually assaulting her when they were teenagers. Pundits viewed it as presenting the classic "he said, she said" scenario, and The Atlantic, The Washington Post, The National Review and the Conservative Tribune ran articles taking varying positions on who had the burden of proving the accusations and whether they needed to be established beyond a reasonable doubt.
The debate among these commentators seemed to rest on the assumption that the legal paradigm for assigning burdens of proof is relevant to confirmation hearings, and differed over whether the highest burden of proof (beyond a reasonable doubt) was the applicable one.
But is the first assumption valid?
Article II, section 2 of the Constitution grants the President the "Power" to "nominate" the "Judges of the supreme Court" "with the Advice and Consent of the Senate," but it says nothing about the procedures for granting that Advice and Consent. Because these procedures are unregulated by the Constitution, confirmation hearings are not bound by the legal paradigm for assigning and defining burdens of proof.
And even if the Senate decided to incorporate the legal paradigm governing burdens of proof into its confirmation hearings, that begs the same two questions attendant to any burden of proof: Who should bear the burden, and what should it be?
Does the president have the burden of establishing that his nominee is qualified and fit for office? Does the nomination itself erect a rebuttable presumption of fitness?
The type of burden turns chiefly on what is at stake. With confirmation hearings, it is a job interview. Does that warrant something lesser than the beyond a reasonable doubt standard that applies when liberty is at risk? Does it matter if the allegations against a nominee also constitute a crime?
These are complex and difficult questions. Blessedly, I don't have the burden of providing any answers.