Contributory negligence is a common law tort rule (created by judges in court opinions, judicial decisions, or case law) that bars or prevents a plaintiff from recovering on a claim for negligence if the plaintiff contributed to the cause of the accident (was contributorily negligent) in any way. This rule may be referred to as pure comparative negligence.

Some states still apply the contributory negligence rule. But because of the harsh outcome of the contributory negligence rule, many state legislatures have enacted statutes that provide for comparative negligence or fault and reduce the plaintiff’s recovery by the amount of the plaintiff’s negligence or fault. This rule may be referred to as pure comparative fault.

Other states have enacted a modified comparative fault statute or law that reduces a plaintiff’s recovery by the plaintiff’s percentage of fault, but bars a plaintiff from any recovery if the plaintiff is 50% or more at fault for the cause of the accident.

And in South Dakota, the comparative fault system uses a slight/gross negligence system and only analyzes the comparative fault if the plaintiff’s negligence is slight and the defendant’s negligence is gross. Under this slight/gross negligence system, if the plaintiff’s negligence is more than slight and the defendant’s negligence is less than gross, the plaintiff is barred or prohibited from any recovery.

These contributory negligence and comparative fault laws vary from state to state and may change or evolve at any time—whether they are located in court opinions or in statutes.

In Arizona, the rule of pure comparative negligence applies. Under this system, a plaintiff can recover damages even if they are found to be 99% at fault for the accident. The plaintiff's recovery is reduced by their percentage of fault. For example, if a plaintiff is awarded $100,000 in damages but is found to be 30% at fault, they would receive $70,000. This approach is more lenient than the contributory negligence rule, which would bar recovery entirely if the plaintiff is found to have any degree of fault. Arizona's adoption of the pure comparative negligence rule allows for a more equitable distribution of damages based on the degree of fault attributed to each party involved in an accident.