Contributory negligence is a legal rule that applies when someone causes harm to another person, but the person who has been harmed might be somewhat responsible for the harm caused to them. For example, if someone got hit by a car while crossing the street, but they crossed against the traffic light and didn't look both ways before crossing, this could be considered contributory negligence. The driver would still mainly be responsible, but the person who crossed the street could also be partly responsible for the accident happening.