A failure to behave with the level of care that someone of ordinary prudence would have exercised under the same circumstances. The behavior usually consists of actions, but can also consist of omissions when there is some duty to act (e.g., a duty to help victims of one's previous conduct).
Primary factors to consider in ascertaining whether the person's conduct lacks reasonable care are the foreseeable likelihood that the person's conduct will result in harm, the foreseeable severity of any harm that may ensue, and the burden of precautions to eliminate or reduce the risk of harm. See Restatement (Third) of Torts: Liability for Physical Harm § 3 (P.F.D. No. 1, 2005). Negligent conduct may consist of either an act, or an omission to act when there is a duty to do so. See Restatement (Second) of Torts § 282 (1965).
Five elements are required to establish a prima facie case of negligence: the existence of a legal duty to exercise reasonable care; a failure to exercise reasonable care; cause in fact of physical harm by the negligent conduct; physical harm in the form of actual damages; and proximate cause, a showing that the harm is within the scope of liability.
- The Harvard Bridge Project article on Negligence vs. Strict Liability from a law and economics perspective