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 Texas, the rule of comparative fault, also known as proportionate responsibility, is codified in the Texas Civil Practice and Remedies Code, specifically in Chapter 33. According to Texas law, if a plaintiff is found to be partially at fault for an accident or injury, their recovery of damages can be reduced by their percentage of fault. However, if the plaintiff is more than 50% responsible for the incident, they are barred from recovering any damages. This is known as a 'modified comparative fault' system. It is different from a 'pure comparative fault' system, where a plaintiff can recover damages no matter how much they are at fault, with the recovery simply reduced by their percentage of fault. Texas does not follow the slight/gross negligence comparative fault system like South Dakota. It's important to note that these laws can be subject to change, and an attorney can provide the most current advice on how comparative fault may affect a particular case in Texas.