Establishing the four elements of negligence
Negligence requires proof of four elements, each of which the plaintiff must establish by preponderance of the evidence. First, the defendant owed a duty of care to the plaintiff, meaning the defendant was legally obligated to act reasonably under the circumstances. This duty exists broadly among all people to avoid conduct that creates unreasonable risk of harm to others. Second, the defendant breached that duty by acting or failing to act in a way that fell below the standard of care.
Third, the breach caused injury to the plaintiff, both in fact (but-for causation: the injury would not have occurred but for the breach) and in law (proximate cause: the injury was a foreseeable consequence of the breach). Fourth, the plaintiff suffered actual damages, whether physical injury, property damage, emotional harm, or economic loss. The defendant is not liable for hypothetical or speculative injuries.
Defenses and modified comparative fault
Defendants can defend by disputing any element. They might argue no duty existed, that the plaintiff assumed the risk, or that the plaintiff's own negligence contributed to the injury. Comparative negligence rules, now adopted in most jurisdictions, allow a plaintiff to recover even if partially at fault, as long as the plaintiff's share of blame is less than the defendant's (or less than 50 percent in pure comparative jurisdictions).
Some jurisdictions follow modified comparative negligence, barring recovery if the plaintiff is 50 percent or more at fault. Others apply pure comparative negligence, reducing damages by the plaintiff's percentage of fault regardless of how small the defendant's share. This framework has largely replaced the old rule of contributory negligence, which barred any recovery if the plaintiff bore any share of fault.