Definition
The weight of evidence is the relative persuasive force or convincing power of the evidence on one side of a dispute compared to the evidence on the other. It is distinct from the mere quantity of evidence: more evidence does not automatically mean greater weight. Weight turns on credibility, consistency, corroboration, and the inherent plausibility of what the evidence tends to prove.
The concept operates at two levels in legal practice:
1. As a standard for new trials. A court may grant a new trial when a verdict is against the weight of the evidence — meaning the jury's conclusion, while perhaps supported by some evidence, runs contrary to the preponderant force of the credible proof. This is a narrower ground than "no evidence" or "insufficient evidence" as a matter of law.
2. As a descriptor of the burden-meeting threshold. In civil litigation, the party bearing the burden of proof must produce evidence whose weight tips the scales in their favor — the familiar preponderance standard. In criminal proceedings, the prosecution's evidence must carry sufficient weight to establish guilt beyond a reasonable doubt.
Common Language
Modern common usage (Wiktionary): "Weight of evidence" in ordinary English refers broadly to the overall force or amount of evidence supporting a conclusion — used freely in science, journalism, and everyday argument to mean something like "most of the evidence points this way."
Historical common usage (Webster's 1913): Webster's treats the phrase as largely self-explanatory, consistent with the general sense of relative heaviness or preponderance.
The gap is meaningful. In common usage, "weight of evidence" collapses into "amount of evidence." In legal usage, weight is a quality judgment, not a counting exercise. A single eyewitness account may outweigh a stack of circumstantial inferences; hearsay admitted without objection may carry very little weight despite its volume. Researchers who carry the ordinary-language sense into legal sources risk misreading how courts and advocates deploy the term.
Common Confusion
Weight of evidence is frequently confused with sufficiency of evidence, but they are distinct legal inquiries. Sufficiency is a legal question: was there enough evidence, as a matter of law, for a rational factfinder to reach the verdict? A court reviews sufficiency without reweighing credibility. Weight is a factual question — was the jury's assessment of competing proof so contrary to the preponderant force of the evidence that justice requires a new trial? A verdict may be legally sufficient yet still be against the weight of the evidence, and vice versa. Motions for judgment as a matter of law target sufficiency; motions for a new trial on weight grounds are a separate remedy with a higher practical bar.
Why It Matters in Research
Researchers face three recurring traps when working with "weight of evidence" across the Law Mind corpus.
First, the new-trial doctrine is where this term does most of its work in reported opinions. Courts are explicit that the power to grant a new trial on weight grounds is exercised rarely and with great caution — as Bouvier notes, with "strict and sure judgment." Researchers looking at historical opinions should expect to find the phrase used almost exclusively in this procedural context, not as a freestanding evidentiary rule.
Second, the term is jurisdictionally unstable in a subtle way. Some jurisdictions treat appellate review of "against the weight" findings as virtually unreviewable; others permit limited appellate scrutiny. The standard for what counts as "against the weight" also varies. Historical sources, including Black's and Bouvier's, do not capture this variation — they describe the concept at a level of generality that masks significant differences in how the doctrine operates in practice.
Third, do not confuse weight of evidence discussions in civil and criminal contexts. In criminal cases, the against-the-weight standard for new trials coexists with the constitutional sufficiency standard derived from federal due process doctrine. When researching criminal procedure sources in the corpus, these two threads often appear in the same opinion and can be conflated.
Historical Dictionary Support
Black's and Bouvier's agree on the core definition: weight of evidence means the balance or preponderance — the greater inclinatory force of the credible proof on one side. Both sources anchor the concept in the new-trial context.
Bouvier's entry is the more substantive of the two, explicitly noting that courts will not exercise the power to grant a new trial on weight grounds lightly. This reflects a historical judicial posture that remains recognizable in modern practice, though the doctrinal framework around it has become more elaborate.
Black's entry, as preserved in the Law Mind corpus, is truncated and partially garbled — the surviving text runs into an unrelated entry (WEREGELT THEF) without completing the definition. Researchers relying on Black's alone will find the entry incomplete. Bouvier's should be treated as the primary historical source for this term.
Neither dictionary addresses the distinction between weight and sufficiency with any analytical precision — that conceptual separation developed more clearly through twentieth-century procedural doctrine. Researchers should not expect to find the modern weight/sufficiency distinction articulated in either historical source.
Jurisdictional Note
The against-the-weight-of-the-evidence standard for new trials is recognized in both federal and state courts, but the precise formulation and appellate reviewability differ by jurisdiction. Federal appellate courts generally give substantial deference to trial court rulings on weight-based new-trial motions. Several states impose explicit limitations on when and how often a new trial may be granted on this ground.
Encyclopedia Cross-Reference
Rules of Evidence in Criminal Cases (Overview) (The Law Mind Criminal Law Encyclopedia)
Pretrial Motions — Motion to Suppress Evidence (The Law Mind Criminal Law Encyclopedia)