Arrest or custodial arrest is the process in which the police take physical possession or custody of a person whom they have probable cause to believe committed a criminal offense. Arrest is distinguishable from other circumstances in which the police stop, detain, or otherwise interact with persons because it is generally the point at which a person is not free to leave or walk away from the police. Arrest is also the point at which some Constitutional rights and protections are provided to the accused. A person who is placed in handcuffs or otherwise physically restrained is clearly under arrest—but in some circumstances a person may be under arrest due to threats or intimidation from the police.

In Idaho, as in other states, an arrest or custodial arrest occurs when law enforcement takes a person into physical custody based on probable cause that the person has committed a criminal offense. The distinction between an arrest and other forms of police interaction, such as a stop or detention, lies in the individual's freedom to leave. Once arrested, the individual is not free to walk away from the police. The use of handcuffs or other physical restraints typically signifies an arrest, but an arrest can also occur if the police use threats or intimidation to detain a person. Upon arrest, certain Constitutional rights are triggered, including the right to remain silent and the right to an attorney. These rights are protected under the Fourth Amendment, which guards against unreasonable searches and seizures, and the Fifth and Sixth Amendments, which provide for due process and the right to counsel. Idaho state statutes and federal law govern the procedures and rights associated with an arrest.