What is one requirement for conducting a search incident to arrest?

Conducting a search incident to arrest is primarily justified when the arrest is lawful and custodial. This means that the law enforcement officer must have a valid reason—such as probable cause—to detain the individual legally. A lawful arrest provides the legal framework under which officers can conduct a search of the arrestee and the immediate area within their control. This is intended to ensure officer safety, prevent the destruction of evidence, and secure any weapons that might pose a risk during the arrest process.

Other options like requiring the arrestee to be of legal age or needing an explicit consent for the search do not align with the established legal principles surrounding searches incident to arrest. Similarly, the requirement for searches to be conducted in plain view pertains to a different legal doctrine regarding searches and seizures rather than being specifically linked to the context of a lawful arrest. Thus, for a search to be valid in this instance, the arrest itself must be lawful and custodial, making that the correct requirement for conducting a search incident to arrest.