Definition
A tort doctrine that apportions fault between a negligent plaintiff and a negligent defendant, reducing — or in some systems eliminating — the plaintiff's recovery in proportion to the plaintiff's own share of fault. It replaces or modifies the all-or-nothing bar of contributory negligence, which historically denied any recovery to a plaintiff who contributed even slightly to their own injury.
Under comparative negligence, the factfinder assigns each party a percentage of fault. The plaintiff's damages award is then reduced by that percentage. Whether the plaintiff recovers anything at all depends on which system the jurisdiction applies.
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Common Confusion
COMPARATIVE NEGLIGENCE vs. CONTRIBUTORY NEGLIGENCE: These are not variants of the same rule — they are competing doctrines. Contributory negligence is a complete bar: any fault on the plaintiff's part defeats the entire claim. Comparative negligence is a proportional reduction. Most American jurisdictions have replaced contributory negligence with some form of comparative negligence, but a small number retain contributory negligence as a complete bar. Historical sources — including both Black's and Bouvier's entries reproduced here — use "comparative negligence" to describe a narrow, now-archaic version of the doctrine involving the "slight/gross" sliding scale, not the modern percentage-based systems. A researcher who reads those entries without context will find a doctrine that is largely obsolete.
COMPARATIVE NEGLIGENCE vs. COMPARATIVE FAULT: Often used interchangeably in practice, but "comparative fault" is technically broader. Comparative fault can encompass intentional conduct, strict liability defendants, and non-party actors. Comparative negligence, strictly read, applies to negligent conduct only. Statutes and courts frequently conflate the terms; check the governing statute's language.
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Core Elements
For a comparative negligence apportionment to apply, the following must be established:
1. The plaintiff suffered damages caused by the defendant's negligence.
2. The plaintiff's own negligent conduct also contributed to the harm.
3. The factfinder assigns percentage shares of fault to each party (and, in many modern systems, to any additional responsible parties).
4. The plaintiff's damages are reduced by the plaintiff's percentage of fault.
5. If the jurisdiction follows a modified system, the court applies the applicable threshold to determine whether recovery is barred entirely.
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Recognized Forms
/SUBTYPES
Pure Comparative Negligence: The plaintiff recovers regardless of their percentage of fault. A plaintiff found 90% at fault recovers 10% of total damages. No threshold bars recovery. California, New York, and a minority of states follow this model.
Modified Comparative Negligence — 50% Bar Rule: The plaintiff recovers only if their fault does not reach 50%. At exactly 50%, recovery is barred. A plurality of states follow this variant.
Modified Comparative Negligence — 51% Bar Rule: The plaintiff recovers only if their fault is 50% or less — that is, as long as the plaintiff is not more at fault than the defendant. At 51% or more, recovery is barred. This is the most widely adopted modified variant.
Slight/Gross Rule (Historical): The plaintiff recovers only when their negligence is "slight" and the defendant's is "gross." This is the form defined by Black's and Bouvier's. It survives in only one or two jurisdictions and is otherwise obsolete.
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Why It Matters in Research
The historical dictionary entries here — both Black's and Bouvier's — define comparative negligence exclusively through the slight/gross framework. That definition is accurate for the nineteenth-century common law and for a transitional period in American tort law, but it does not describe what comparative negligence means in any major jurisdiction today. A researcher reading those entries without understanding this shift will mistake an archaic minority rule for current doctrine.
The doctrinal transformation occurred primarily through legislative reform in the 1960s through 1980s. Most states abolished or limited contributory negligence by statute, not by judicial decision, so the relevant authority is statutory rather than in case law reporters. When researching any particular state's rule, the governing text is the apportionment statute, not common law doctrine.
For multi-defendant cases, comparative negligence intersects directly with joint and several liability rules, which vary enormously by jurisdiction. Some states have abolished joint and several liability alongside adopting comparative fault; others retain it; still others apply hybrid rules based on a defendant's percentage of fault. These combinations create research complexity that neither the tort doctrine alone nor the comparative negligence rule alone will reveal — the researcher must trace both threads simultaneously.
In products liability contexts, comparative fault is applied differently across jurisdictions: some apply it to strict liability claims, some do not, and the treatment of product misuse as a comparative fault issue versus a superseding cause is unsettled in a number of states. See torts_81 for the products liability intersection.
Historical sources also sometimes treat assumption of risk as a separate defense alongside comparative negligence. Under most modern comparative fault regimes, implied assumption of risk has been folded into comparative fault analysis rather than treated as an independent complete bar. Express assumption of risk generally survives as a separate defense.
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Historical Dictionary Support
Black's and Bouvier's entries are nearly identical and reflect the same doctrinal moment: a period when comparative negligence was understood as a limited judicial or legislative softening of contributory negligence, not a wholesale replacement. Both sources describe the slight/gross tripartite framework — "slight," "ordinary," and "gross" negligence — as the operative mechanism for comparison. Both entries are truncated in the versions available here, but the substance is clear: recovery was permitted only when plaintiff's fault was slight and defendant's was gross.
This formulation is historically important as a transitional step. It acknowledged the harshness of pure contributory negligence without abandoning the underlying fault hierarchy. The modern percentage-based system, which makes no reference to these qualitative grades, represents a fundamentally different approach that these sources do not anticipate. Neither dictionary entry addresses multi-party apportionment, pure systems, or statutory reform — all of which are essential to modern research. Use these entries for historical context only.
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Jurisdictional Note
A small number of states — including Alabama, Maryland, North Carolina, and Virginia — retain contributory negligence as a complete bar. In those jurisdictions, comparative negligence as a doctrine does not apply to plaintiff's fault, though related apportionment rules may apply among defendants. In all other states, the applicable comparative negligence or comparative fault statute controls, and its specific threshold and apportionment method must be confirmed before relying on any general statement about the doctrine.
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Encyclopedia Cross-Reference
Torts & Personal Injury Encyclopedia, torts_22: Defenses to Negligence — Comparative Fault (Pure vs. Modified Systems) — primary reference for the full taxonomy of systems, threshold rules, and multi-party apportionment.
Torts & Personal Injury Encyclopedia, torts_81: Products Liability — Defenses (Misuse, Alteration, Comparative Fault) — for the application of comparative fault in strict liability and products contexts.
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