Tort Law - Negligence
If a plaintiff is found to have acted to their own detriment in a situation, so that they are partially or wholly responsible for the harm they are suing for, then either their claim is defeated, or the sum they can recover in damages is reduced. There are two elements to contributory negligence:
Did the plaintiff do what they should have done to take care of themselves?
If not, did their failure to take reasonable care contribute to the harm that was suffered?
If a certain precaution is commonly understood by the general public, then the plaintiff is held to have been negligent in not taking such a precaution. Examples are a car accident resulting in injury due to failure to wear a seatbelt (irrespective of the road rules), or crossing a road without streetlights, wearing dark clothing, in a fog and being struck by an approaching vehicle.
The latter example comes from Pennington v Norris. The High court was asked whether the 50 percent reduction in damages at the trial should be reduced. The High Court ruled that the blame of the defendant driver was much greater than the blame of the plaintiff pedestrian...
ORDER FOR FULL TEXT.
 Pennington v Norris (1956) 96 CLR 10.
 Caterson v Commissioner for Railways (1973) 128 CLR 99.