Maryland v. King, 569 U.S. 435 (2013), was a decision of the United States Supreme Court which held that a cheek swab of an arrestee's DNA is comparable to fingerprinting and therefore, a legal police booking procedure that is reasonable under the Fourth Amendment.

It concluded that it is constitutionally reasonable for the state to undertake the "negligible" physical intrusion of swabbing the inside of the legitimately detained arrestee's cheeks and using limited data from the DNA to determine whether the individual might be associated with a crime scene or victim.

King filed a motion to suppress the DNA evidence, stating that it infringed upon his Fourth Amendment rights, which prohibit unreasonable searches and seizures, in the Circuit Court for Wicomico County.

The Maryland Court of Appeals then reversed the original ruling, agreeing that the DNA sampling was a violation of the Fourth Amendment and could not be used as evidence.

[2] Dr. Steven D. Schwinn's article titled "Fourth Amendment," published by the American Bar Association, best gives a full detailed progression of the case.

The majority opinion, written by Justice Anthony Kennedy, described Maryland's law as follows: The Act authorizes Maryland law enforcement authorities to collect DNA samples from "an individual who is charged with... a crime of violence or an attempt to commit a crime of violence; or... burglary or an attempt to commit burglary."

The collection of genetic markers allows for high precision identification of a suspected criminal from the DNA samples found at crime scenes or on victims.

The genetic markers from an individual are searched against all other felons and arrestees in the database when police are attempting to compile evidence by the use of blood, saliva, skin, or other bodily fluids.

The extent to which the case is a move toward replacing the rule that warrants must be based on probable cause, normally required with a general standard of reasonableness in Fourth Amendment jurisprudence, has been debated.

The overall ruling is that it not a violation of the Fourth Amendment in that these samples are part of the protocol when a person is arrested for a serious or violent crime, and the DNA get placed in the system and not be removed except on request.

DNA testing is not analogous to fingerprinting but an invasion of privacy that citizens have the "right to secure their persons, houses, papers, and effects."

As for the plaintiff, the Maryland DNA Collection Act serves as a well-established, legitimate booking procedure for all individuals indicted on charges of violence or burglary.

[11] The act and the Maryland state CODIS database were established to keep communities safe by improving the criminal justice system and police investigation practices.

The dissenting view claims that the potential benefits of finding actual perpetrators of cold cases and the possibility of freeing those wrongly convicted do not outweigh the critical privacy concerns.