Also known as:preponderance of the evidence · preponderance of evidence standard · preponderance of evidence · preponderance
Written by attorneys · grounded in primary & secondary sources — see below
A burden of proof requiring the party bearing it to establish that a contested fact is more likely true than not true.
Sources & Authorities
How it applies
Common Examples
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Probate Slayer Determination
Preston Pratt petitioned the probate court to bar his sister Penelope Price from inheriting under their mother's will after the plane crash that killed her. The court weighed the pre-flight modifications to the controls, Penelope's recent comments about assuming leadership, and the absence of any qualifying criminal conviction. Finding it more likely than not that Penelope had feloniously and intentionally caused the death, the court applied the preponderance standard and denied her the devise.
Prior Acts Evidence Ruling
The prosecution sought to introduce Pavel Petrov's earlier diversion of nonprofit funds to show motive and absence of mistake in the current embezzlement charges. The trial court examined the invoices and board minutes but made no preliminary finding that the prior acts had been proved by a preponderance. It admitted the evidence after determining that a reasonable jury could find the acts occurred and that their probative value on non-propensity issues was not substantially outweighed by unfair prejudice.
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Cases
Statutes
Uniform Acts
Model Codes
Restatements
Casebooks
Hornbooks
Study Supplements
Will Ambiguity Resolution
Patrick Phan and Pamela Phillips each claimed the training-facility shares under the coach's will devising them to the player who captained my toughest team. The executor presented extrinsic evidence of the coach's statements about both claimants' squads and the two facilities he owned. The probate court found that the donor's intention to benefit Patrick was established by a preponderance of the evidence and distributed the shares accordingly.
Expert Testimony Gatekeeping
Peak Performance sued Phoenix Technologies alleging that a chemical exposure caused birth defects. The district court evaluated the plaintiffs' epidemiological studies under the Daubert factors to decide whether the expert testimony was admissible. After determining that the relative-risk data satisfied the preponderance threshold for reliability, the court permitted the testimony to reach the jury.
Daubert v. Merrell Dow Pharmaceuticals, Inc.509 U.S. 579, 592 (1993)
Juvenile Delinquency Finding
The state charged a juvenile with arson and sought to prove the allegations in family court. The court considered whether the preponderance standard could be applied to the evidence of the juvenile's participation and intent. The Supreme Court held that due process requires proof beyond a reasonable doubt rather than a mere preponderance and reversed the delinquency adjudication that had rested on the lower standard.
In re Winship397 U.S. 358, 364, 90 S.Ct. 1068, 1073, 25 L.Ed.2d 368 (1970)
Ineffective Assistance Claim
Perry Pratt moved to vacate his conviction on the ground that trial counsel failed to investigate an alibi. The court required Pratt to prove by a preponderance of the evidence both that counsel's performance fell below an objective standard of reasonableness and that the deficient performance prejudiced the defense. After weighing the affidavits and record, the court denied relief.
Strickland v. Washington466 U.S. 668 (1984)
Common questions
Frequently Asked
5
What quantum of proof does the preponderance standard require?+
The standard requires the party with the burden to show that the existence of a fact is more probable than its nonexistence. Primary authorities apply this test in civil proceedings such as slayer determinations and will construction.
Does the preponderance standard apply to preliminary questions of fact when admitting evidence under Rule 404(b)?+
No preliminary finding by the judge that the prior act was proved by a preponderance is required. The evidence is admissible if a reasonable jury could find the act occurred and the probative value on a non-propensity issue is not substantially outweighed by unfair prejudice.
How does the preponderance standard interact with a final criminal conviction in a slayer proceeding?+
A final judgment of conviction for the felonious and intentional killing conclusively establishes slayer status in the civil proceeding. Absent such a conviction the court must independently determine slayer status under the preponderance standard.
Is the preponderance standard constitutionally sufficient to terminate parental rights?+
No. Due process requires clear and convincing evidence to terminate parental rights. A mere preponderance standard is constitutionally insufficient.
What burden applies when a defendant asserts an affirmative defense under the Model Penal Code?+
The defendant must prove the defense by a preponderance of the evidence. This allocation applies to defenses such as entrapment, mental disease or defect, and certain mistake-of-law claims.
397 U.S. 358, 90 S. Ct. 1068, 25 L. Ed. 2d 368 (1970)Criminal Procedure
…that "[a]ny determination at the conclusion of [an adjudicatory] hearing that a [juvenile] did an act or acts must be based on a preponderance of the evidence."[^maj-2] During a subsequent dispositional hearing, appellant was ordered placed in a training school for an initial period of 18 months, subject to annual extensions of his commitment…