## Facts

- Alonzo Jay King, Jr. was arrested in Maryland in 2009 for first- and second-degree assault and booked into custody.
- During booking, officers collected a buccal (cheek) swab DNA sample under the Maryland DNA Collection Act, which authorized DNA collection from persons arrested for certain violent crimes and burglaries.
- King’s DNA profile was entered into the state database and matched DNA from an unsolved 2003 rape.
- A grand jury indicted King for the rape; police obtained a second buccal swab for evidentiary use.
- King moved to suppress the DNA evidence, arguing the initial warrantless DNA collection violated the Fourth Amendment.
- The trial court denied suppression; King was convicted of first-degree rape and sentenced to life imprisonment.
- The Maryland Court of Appeals reversed, holding the Act’s arrestee-DNA provisions unconstitutional under the Fourth Amendment.
- The U.S. Supreme Court granted certiorari.

## Issues

1. Whether the Fourth Amendment permits warrantless collection and analysis of an arrestee’s DNA by cheek swab, as part of routine booking for a serious offense supported by probable cause.

## Decision

- The Supreme Court reversed the Maryland Court of Appeals in a 5–4 decision authored by Justice Kennedy.
- The Court held that taking and analyzing a cheek swab from a person lawfully arrested and held for a serious offense is a reasonable Fourth Amendment search when conducted as part of standard booking, similar to fingerprinting and photographing.
- The Court emphasized the minimal physical intrusion of a buccal swab and the limited nature of the DNA analysis used for identification.
- The dissent (Justice Scalia, joined by Justices Ginsburg, Sotomayor, and Kagan) argued the practice was suspicionless evidence-gathering for unrelated crimes and violated the Fourth Amendment’s bar on searching for evidence without particularized cause.

## Legal Principles

- A buccal swab for DNA is a Fourth Amendment “search,” but its validity may be assessed under a general reasonableness balancing approach in the context of a lawful custodial arrest for a serious offense.
- For arrestees lawfully held on probable cause, privacy expectations are reduced as to routine administrative procedures incident to arrest and detention.
- DNA identification may be treated as an extension of established booking identification methods (fingerprinting and photographing) when used to confirm identity and connect the arrestee to law enforcement records.
- Reasonableness may be supported by the method’s minimal intrusion and by statutory limits and safeguards restricting collection, analysis, retention, and use of arrestee DNA.

## Conclusion

The Court held that Maryland’s warrantless collection and analysis of a cheek swab DNA sample from a serious-offense arrestee during booking is a reasonable search under the Fourth Amendment, analogizing DNA identification to traditional booking procedures and applying a balancing of reduced arrestee privacy against government interests in identification and custody-related decisionmaking.


Maryland v. King, 569 U.S. 435 (2013)