The Fourth Amendment and Searches For Criminal Suspects

In general, police must obtain a search warrant before searching a suspect’s belongings or residence. However, there are exceptions.


During the booking process, an officer will take your mug shot and fingerprints. This information is entered into a database.

Police can conduct a protective sweep without a warrant when they have reasonable suspicion that the person may gain possession of a weapon or destroy evidence. This search must be contemporaneous with the arrest.


When a person is arrested, they are taken to jail and “booked.” During this process, police enter the person’s name and basic personal information into a computer system. They also collect fingerprints and photographs (often called mug shots) and record the nature of the suspected crime. Additionally, they search databases to find out whether the suspect has any outstanding warrants.

Jail officials usually ask the arrestee to list all their known gang affiliations and outside relationships. This helps them determine if the suspect is likely to be dangerous, which might require them to place him in protective custody or house him in one section of a jail rather than another. Depending on the answers, this might or might not constitute an “interrogation” that requires officers to give the suspect their Miranda warning.

During the booking process, police personnel typically conduct medical screenings to make sure that the suspect is not in need of immediate care or is a threat to jail staff members and other inmates. Depending on the case, these may include X-rays and blood tests for TB or sexually transmitted diseases.

In addition, a suspect might undergo a strip search as part of the booking process. This is designed to prevent weapons and drugs from entering a jail facility. It involves removing all clothing and having the suspect stand for photos in front of a police officer or a photographer. In some jurisdictions, the officers involved in a strip search are trained to use a blinded procedure. This entails placing the suspect’s photo in the top folder, and the photographs of the fillers in the five other folders. The folders are then shuffled so that the officer does not know which folder contains the suspect’s photo. Medical staff should record the results of any medical screenings in the suspect’s booking file.

Protective Sweep

Police officers often use the term “protective sweep” to describe searches outside the immediate area of a person they have already arrested for weapons and people who could attack them. This search is an exception to the general legal rule that police must have a warrant to enter your home or vehicle.

The Supreme Court in Maryland v. Buie established the protective sweep doctrine that allows officers to search areas near an arrest location for weapons or other dangers. However, the scope of a protected sweep is limited and must be reasonably related to the circumstances in which it occurs. Officers who sweep beyond the immediate area of an arrest can only do so if there is a reasonable belief, based on specific and articulable facts, that other dangerous individuals may be hiding in those areas.

This limitation on the scope of a protective sweep can be difficult for many suspects. While it is true that the protective sweep is only for those individuals who pose a threat to officers, prosecutors and other law enforcement can be quick to characterize this search as a generalized search for evidence. This is incorrect, as police must have a legitimate reason antecedent to the protective sweep in order to justify it.

In a recent case, officers were at the defendant’s house to serve a warrant for an in-home arrest. When they accompanied the defendant to his office in the basement, officers saw that the room contained a gun and a silencer. The officers did not have a warrant, proper consent, or exigent circumstances to enter the apartment for this purpose. The Second Circuit Court of Appeals ruled that these circumstances did not meet the necessary criteria for a protective sweep. The case illustrates how the scope of a protective sweep must be limited in order for it to be valid.

Search Incident to Arrest

A search incident to arrest is one of the few specifically established exceptions to the warrant requirement. Under this doctrine, a police officer can search a suspect’s person and the area within their immediate control after they have been lawfully arrested. The Supreme Court in Robinson held that the interests of officer safety and preservation of evidence outweigh the suspect’s Fourth Amendment rights.

New electronic technologies have complicated the application of this search exception. For example, smartphones have vast amounts of personal data including emails photos contacts lists and text messages which can be accessed by the owner at any time. The EFF is working to help ensure that courts are recognizing that these devices fall within the scope of this search incident to arrest exception.

For example, in United States v. Mercado-Nava, the defendant was stopped by the police for allegedly violating a local ordinance that outlawed face-to-face solicitations. The narcotics dog detected drugs on the defendant and he was promptly arrested. The court found that the search of his truck was reasonable under the search incident to arrest doctrine.

However, when the defendant was handcuffed and placed in the police car he could no longer access the small vial attached to his key chain which contained marijuana. The court held that this search was not justified because it was conducted after the defendant had been restrained and placed in a position where he could not reach his property and the search was not contemporaneous with the arrest and immediately related to the place of the arrest.

The search incident to arrest doctrine applies to items that are a part of the person’s immediate control, meaning that if it is attached to the person’s body or clothing it may be searched as long as the officer has probable cause that the item contains evidence relevant to the case. The search must also be reasonably necessary to achieve the officer’s objective of preserving and protecting evidence.