Booking records provide information about the people who are brought to jail. Because booking creates an official arrest record, arrested suspects who can post bail immediately often can't be released until after the booking process is complete. Even suspects who receive citations in lieu of being taken to jail often must go through a booking process within a few days of their arrest.
At its slowest, the booking process may take hours to complete. How long it takes depends on how many of the standard booking procedures are conducted (explained below), the number of arrestees being booked at the same time, and the number of police officers involved in the booking process.
Below are many of the usual procedures related to booking.
In olden days, this information became part of a handwritten police blotter; now virtually all booking records are computerized.
Mug shots have a variety of possible uses. For instance, a mug shot can help to determine which of two people with the same name was arrested. A mug shot can also help to establish a suspect's physical condition at the time of arrest. The suspect's physical condition at arrest can be relevant to a claim of police use of unlawful force or to whether the suspect had been in an altercation before being arrested.
At a suspect's request, some booking officers allow suspects to keep small personal items like a wristwatch. Any articles taken from the suspect must be returned upon release from jail, unless they constitute contraband or evidence of a crime.
Example: Sticky Fingers is arrested for stealing a calculator. The police seize the calculator at the scene of the arrest. During the booking process, the police find a packet of illegal drugs and a stolen camera in Fingers's backpack. These items will not be returned to Fingers upon his release on bail. The calculator and the camera are evidence of the crime of shoplifting. The drugs are illegal contraband; the police can take them regardless of whether drug charges are filed against Fingers.
Fingerprints are a standard part of a booking record, and are typically entered into a nationwide database maintained by the FBI and accessible to most local, state, and federal police agencies. Comparing fingerprints left at the scene of a crime to those already in the database helps police officers identify perpetrators of crimes.
Police officers routinely make cursory pat-down inspections at the time of arrest. Far more intrusive (and to many people, deeply humiliating) is the strip search that is often part of the booking process. To prevent weapons and drugs from entering a jail, booking officers frequently require arrestees to remove all their clothing and submit to a full body search.
Strip searches are typically legal even when the arrestee has been brought in for a relatively minor crime, such as an infraction, and even when there are no facts that would suggest that the arrestee is carrying a weapon or contraband. In a 2012 case, the U.S. Supreme Court ruled that such a search was legitimate even in the case of a person who was stopped for a traffic violation and arrested for failure to pay an outstanding fine (the fine had in fact been paid long ago). (Florence v. Bd. of Chosen Freeholders of Cty. of Burlington, 132 S. Ct. 1510 (2012).)
The booking officer checks to see if an arrestee has any other charges pending, ranging from unpaid parking tickets to murder charges in other states. Suspects with warrants pending are normally not released on bail.
To protect the health and safety of jail officials and other inmates, the booking process may include X-rays (to detect tuberculosis) and blood tests (to detect sexually transmitted diseases such as gonorrhea and AIDS).
To reduce the likelihood of violence and injuries, jail officials often ask arrestees about gang affiliations, former gang affiliations, and other outside relationships. Depending on the answers, an inmate may have to be placed in protective custody or housed in one section of a jail rather than another. Routine questioning along these lines might or might not constitute an "interrogation" that requires officers to give a Miranda warning to the suspect.
Information that suspects disclose in response to a booking officer's questions can be admissible in evidence under the routine-booking-question exception to Miranda. But in California, for one, incriminating information that an arrestee gives in response to a jailer's question about gang affiliation is generally inadmissible if the defendant hasn't been Mirandized. (Pennsylvania v. Muniz, 496 U.S. 582 (1990), People v. Elizalde, 61 Cal. 4th 523 (2015).)
Suspects may be required to provide DNA samples that are entered in national DNA databases.
For much more on booking, jail, bail, and related topics, talk to an experienced criminal defense attorney. A knowledgeable lawyer should be familiar with the law in your jurisdiction and the local practices and procedures.