There are 3 different types of tort law: negligence, intentional tort, and strict liabilty. All 3 kinds of torts must result in harm to be actionable, although the harm does not need to be tangible. They also all have some overlap with criminal law. The defense test for all torts except strict liability is whether the defendant acted reasonably under the circumstances.
Negligence
A negligence tort is a civil wrong which has been caused by failure to take action appropriate to the area of responsibility. In all cases of negligence, the defendant had a duty to the plaintiff, and breached that duty by failing to take needed action. The failure must have resulted in harm.
Some states allow comparative negligence, where a plaintiff may be found to share responsibility for negligence with the defendant. For example, in Georgia, a plaintiff who is found to share more than 50% of the responsibility will not receive damages, because the net responsibility for the lack of action falls to the plaintiff.
Intentional tort
An intentional tort is a civil wrong which has been caused by an intentional action. Intent must be proven beyond reasonable doubt in all intentional tort cases. If intent is in doubt, the case fails as an intentional tort, but may be actionable as negligence or strict liability.
Intentional torts can be divided into intentional interference with the person and intentional interference with property. Property includes both fixed (real) properties and moveable properties (chattel).
Slander and libel, the 2 forms of defamation, are a type of interference with the person which causes intangible harm to the plaintiff. In a civil tort, the plaintiff must first prove that the statement was false. If the statement was made about a public official, the plaintiff must also prove that the statement was made with the intent to cause harm, or with reckless disregard for the truth.
Strict liability
A strict liability tort is a civil wrong which has been caused by a mistake. An action (actus reus) is required, rather than a status. Due diligence is a defense against strict liability, but the defendant may still have to pay damages under absolute liability.
By far, the most common kind of strict liability tort is products liability, where a manufacturer has made a faulty product but did not intend to do so, or else where intent cannot be proven. Anyone who was harmed by the product can sue under strict liability, even if he is not the person who bought the product. A class action lawsuit may occur where a product has harmed many people.
Other strict liability torts may occur where harm has resulted unintentionally from a potentially dangerous act, which may be a legal or illegal act. For example, a highway construction project with all the correct permits and acting appropriately to those permits may result in flooded houses during a sudden rainstorm because a flood spillway was temporarily blocked. If those houses would not otherwise have been flooded, the construction company may be sued for strict liability.