Rethinking Maryland v. King Amid the Changing Landscape of Technology and Privacy

In a landmark 2013 decision, Maryland v. King, the Supreme Court upheld mandatory DNA collection from arrestees as part of booking procedures, likening cheek swabs to fingerprinting. But 13 years later, renewed public concern about genetic privacy seriously undermines the assumptions underlying King. 

In defending the warrantless collection of arrestees’ DNA, the King majority emphasized that the genetic markers used in law enforcement’s Combined DNA Index System (CODIS) do not reveal medical information. The Court said that the DNA samples stored on CODIS are “junk DNA,” useful only in matching a suspect’s DNA to the profile in CODIS. Under that framework, the Court found the intrusion was “minimal” and analogous to fingerprinting.

The Court’s reasoning relied on two assumptions: that the CODIS markers were limited to identification, and that law enforcement’s use of DNA data would be contained within narrow, government‑controlled repositories. As I will explain, neither assertion holds up given the state of genetic testing today.

Consumer Genomics and Genetic Privacy in 2026 

At the time of King, the Court concluded that the non‑coding sequences collected and stored in CODIS posed virtually zero risk for disclosure of health or personal information. Thirteen years later, the landscape has dramatically shifted. Public awareness of the sensitivity of genetic data has grown dramatically with the rise of direct‑to‑consumer testing. Additionally, new technology has expanded the utility of DNA for police investigation.

In 2025, 23andMe filed for Chapter 11 bankruptcy, which raised significant privacy concerns due to the risk of a private buyer acquiring consumer genetic data and health information. Aside from raising public concern about genetic privacy, the 23andMe scandal presents an opportunity to examine how King’s “minimal intrusion” rationale falters in the age of consumer genomics.

23andMe insists that the type of genetic data it stores on its databases is likely to be unhelpful to police for the same reason the King majority argued. Law enforcement collects “junk DNA” that does not reveal health information while private genetic testing companies collect more sensitive markers for single nucleotide polymorphisms (SNPs). However, post-King research reveals that cross-referencing genetic information stored in CODIS with SNP records contained in non-law enforcement databases actually can reveal private information such as health and identification information.

The rise of investigative genetic genealogy (IGG), famous in the public for helping to solve the Golden State Killer case, also illustrates the greater reach one’s DNA can have. IGG allows police to use one person’s DNA to infer familial relationships and obtain information on that person’s relatives. 

Each of these developments underscores a broader point: Genetic data is durable, mobile, and revealing in ways that were not fully anticipated in King. What the Court once characterized as a narrow, contained category of forensic identifiers now sits within a broader ecosystem of genomic data that puts privacy at great risk.

Privacy as the Straw that Breaks the Camel’s Back?

While much discussion about King today focuses on the privacy interests at stake, Justice Scalia’s famous dissent in King focuses more on the Court’s questionable analogy of DNA and the CODIS database to accepted police practice of warrantless fingerprinting of suspects for identification during the booking process. Future courts reexamining King should consider these other flaws of the King decision: the increased privacy risks in police DNA collection may just be the straw that breaks the camel’s back. 

As Justice Scalia’s dissent points out, the Court’s decision allowed programs that target people that are arrested and not convicted, either by acquittal at trial or due to prosecutors dropping the charges. The parties in King agreed that police could obtain and store a convicted person’s DNA; the fight was over post-arrest, pre-conviction programs.  

In other words, these particular programs collect and retain DNA from significant numbers of innocent people. While mechanisms exist for people in this group to expunge their records, scholars note that expungement is rare due to the procedural barriers and costs often required to obtain it. 

Rethinking King in 2026

None of these new developments or criticisms automatically invalidate King. However, as the King majority itself recognized, “science can always progress further, and those progressions may have Fourth Amendment consequences.” The Supreme Court should seriously consider overruling King: Its “minimal intrusion” rationale, already questionable in 2013, does not hold with the scope of genetic testing and societal expectations around genetic data today. 

Short of formally overruling King, the Supreme Court should at least provide guidance on how genetic privacy concerns intersect with Fourth Amendment protections in an age of more expansive, advanced genetic testing. Modern developments in genetic testing raise several important questions for the Court to answer:

• Should police be required to get a warrant to use the wealth of personal information held by genetic testing companies? In Carpenter v. United States (2018), the Supreme Court determined that police needed a warrant to obtain a person’s cell site location information from private cell phone companies, as an exception to the third-party doctrine (which holds that the Fourth Amendment does not protect information freely given to a third party). 
• Should police be required to get a warrant before obtaining the DNA information for a suspect’s relative from a private genetic testing company? If police can obtain a relative’s information to use in a genetic genealogy search, must they separately obtain consent from the relative? 
• In light of the 23andMe scandal, how might a bankruptcy and subsequent sale of genetic data to another company affect police’s ability to use that data? Does the Fourth Amendment require police to re-obtain users’ consent?

An evidence‑informed reassessment of King can preserve constitutional rights by properly acknowledging the expansive privacy implications of systematic DNA collection programs with current technology and practices.