A more thorough explanation:

Contributory infringement is a type of secondary liability for direct infringement of a patent, copyright, or trademark. It means that a person can be held responsible for infringement even if they did not directly engage in infringing activities.

For patents, contributory infringement is defined by 35 U.S.C. § 271(c). It states that a person who sells or imports a component of a patented invention, knowing that it is made or adapted for use in infringing the patent, can be held liable as a contributory infringer. However, the alleged infringing article or commodity must be unsuitable for any commercial non-infringing use.

For example, if a company sells a part that is specifically designed to be used in an infringing way, they can be held liable for contributory infringement. However, if the part has other lawful uses, they cannot be held liable.

Unlike patents, the Copyright Act does not explicitly impose liability for contributory infringement. However, the U.S. Supreme Court has ruled that a person who knowingly induces, causes, or materially contributes to copyright infringement by another can be held liable as a contributory infringer if they had knowledge or reason to know of the infringement.

For example, if a website provides a platform for users to share copyrighted material illegally, and the website owners know about it but do nothing to stop it, they can be held liable for contributory infringement.

Similarly to copyright, the Lanham Act does not expressly impose liability for contributory infringement. However, the U.S. Supreme Court has recognized that liability for trademark infringement can extend beyond those who actually mislabel goods with the mark of another.

For example, if a company knowingly supplies its product to someone who is engaging in trademark infringement, they can be held liable for contributory infringement.

Overall, contributory infringement is a way to hold people accountable for indirect involvement in infringing activities. It requires knowledge or reason to know of the infringement and that the alleged infringing article or commodity is unsuitable for any commercial non-infringing use.