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Broadly speaking, interference in a legal setting is wrongful conduct that prevents or disturbs another in the performance of their usual activities, in the conduct of their business or contractual relations, or in the enjoyment of their full legal rights. Interference can arise in a variety of legal fields including, but not necessarily limited to, tort law, property law, contract law, business law, election law, patent law, family law, employment law, and criminal law. Many of the claims that arise out of interference are born from an intersection between tort law and some other field.

Tort Law

Tortious interference is a common law tort allowing a claim for damages against a defendant who wrongfully interferes with the plaintiff's contractual or business relationships.

Property Law

 Interference in the context of property law can have several applications. Unlawful interference with another individual’s piece of property may carry civil or even criminal penalties. One example is the crime of trespass, which may be civilly and criminally punishable. Another example of unlawful interference in property law is impermissible interference with another individual’s legal use of their own property to the full extent possible, as illustrated in the case of Keeble v. Hickeringill. In that case, the plaintiff recovered damages from a neighbor who purposefully interfered with the plaintiff's use of his own property to capture ducks.

Contract Law

At common law, a defendant’s intentional interference with contractual relations means that they are liable to pay damages in tort for actions intended to interfere with the plaintiff's contractual relations with a third party. In an intentional interference claim, the burden is on the plaintiff to prove the elements of the claim rather than on the defendant to prove that its acts were justified. According to the case of United Truck Leasing Corp. v. Geltman, to prevail on the claim, plaintiff must prove four elements:

  1. A valid contract existed,
  2. The defendant had knowledge of the contract,
  3. The defendant acted intentionally and improperly, and  
  4. The plaintiff was injured by the defendant’s actions.

Business Law

The case of International  News  Service (INS)  v.  Associated  Press (AP) provides a good example of interference arising in a business law context. Here, the Court found that INS’s practice of copying news from AP bulletin boards or early editions and printing it as their own constituted unauthorized interference with AP’s legitimate business and, therefore, created unfair competition in the trade.

Election Law

Election interference may refer to electoral fraud, vote buying (when a political party or candidate distributes money to a voter with the expectation that they will vote for them), voter impersonation (when an eligible voter votes more than once or a non-eligible voter votes under the name of an eligible one), or foreign electoral interference (attempts by governments to influence elections in another country).

Patent Law

In patent law, interference designates a collision between rights claimed or granted; that is, where a person claims a patent for the whole or any integral part of the ground already covered by an existing or pending patent. Strictly speaking, an “interference” is declared to exist by the patent office whenever it is that two pending applications (or a patent and a pending application), in their claims or essence, cover the same discovery or invention, as illustrated in the case of Lowrey v. Cowles Electric Smelting.

Family Law

In family law, interference may arise from actions that disrupt the custodial or visitation rights of parents or guardians. For example, one parent preventing the other from having access to their child or attempting to alienate the child from the other parent. Another example may be one individual interfering in an attempt to carry out a decedent’s wishes, as in the case of Eugene Sonnier, II v. The Catholic Foundation of the Diocese of Lafayette, et al

Employment Law

Interference may arise in the context of employment law, such as interference with employment contracts or interference with labor rights. For instance, an employer interfering with an employee's right to join a labor union or engage in protected activities under labor laws. Legal protections are in place to safeguard employees from such interference.

Criminal Law

Unlawful interference may also carry criminal penalties in the context of criminal law when an individual or entity interferes with “the course of justice” (obstruction of justice) by doing things such as committing perjury or purposefully hindering law enforcement in an investigation.

[Last updated in June of 2023 by Iain Richards with the Wex Definitions Team]