Negligence per se is negligence due to the violation of a public duty under a law that defines the failure of care required to constitute negligence. For example, driving laws may specify that exceeding a certain rate of speed is legally negligent. Negligence per se may also be declared when a person does or omits to do something which is so beyond reasonable behavior standards that it is negligent on its face.
Some acts are considered inherently negligent, with no requirement to prove the negligence was known or intended. For instance, when a doctor leaves a sponge inside a patient, it is inherently negligent. In appropriate cases, affirmative defenses such as contributory negligence, etc., may also be raised by a defendant.