Comparative fault—also known as comparative negligence—is a rule of tort law for allocating liability when two or more parties to an accident or liability incident are at least somewhat at fault.

For example, in a case in which both the plaintiff and the defendant were negligent, the jury may be asked to apportion the liability or responsibility for the accident (and the resulting damages) between the parties—usually as a percentage of each party's negligence—and the plaintiff’s recovery against the defendant may be offset or reduced by the amount of the plaintiff’s negligence. 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.

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 Rhode Island, the rule of comparative fault, also known as comparative negligence, is applied in cases where multiple parties share responsibility for an accident or injury. Under Rhode Island law, a plaintiff's recovery is reduced by their percentage of fault. However, unlike some states that bar recovery if the plaintiff is 50% or more at fault, Rhode Island follows a pure comparative fault system. This means that a plaintiff can recover damages even if they are found to be 99% at fault, although their recovery would be significantly reduced according to their degree of fault. The allocation of fault and the determination of damages are typically decided by a jury. It's important to note that these laws can be subject to change and may be interpreted differently by courts over time.