A more thorough explanation:

Definition: Third-party consent refers to a person's agreement to official action, such as a search of premises, that affects another person's rights or interests. For the consent to be effective for a search, it must be based on the consenting person's common authority over the place to be searched or the items to be inspected.

Example: If a police officer asks a roommate if they can search their shared apartment, and the roommate agrees, this would be an example of third-party consent. However, for the consent to be valid, the consenting roommate must have the legal authority to permit the search in their own right, and the defendant must have assumed the risk that a fellow occupant might permit a search.

This concept is important in criminal law because it allows law enforcement officials to conduct searches and seizures without a warrant if they have obtained valid third-party consent. However, it is essential that the consent is given voluntarily and by someone who has the legal authority to do so.