Genetic Genealogy and the Fourth Amendment

Florida is not alone. The technique has helped solve more than 600 cold cases nationwide since it identified the Golden State Killer in 2018, and Texas law enforcement agencies already use it. The question that press releases underemphasize is the one defense lawyers have to answer: what does any of this mean for a defendant?

The constitutional framework is unsettled, the defense challenges are real, and the technology is outrunning the law. This post is about that law and that defense. For how the technique actually works, and a Texas cold case that shows it in action, see our companion post on cold-case hair analysis and genetic genealogy.

What Genetic Genealogy Is, in Brief

Forensic investigative genetic genealogy, or FIGG (the Department of Justice calls it forensic genetic genealogy searching, or FGGS), is not the CODIS database that police have used for decades. CODIS matches a short-tandem-repeat profile from a crime scene against profiles from known offenders, arrestees, and other cases; if the suspect is not already in it, CODIS cannot help. FIGG works differently. A laboratory like Othram takes a crime-scene sample, generates a dense profile of hundreds of thousands of single-nucleotide polymorphisms, and uploads it to a consumer ancestry database such as GEDmatch or FamilyTreeDNA. The goal is not an exact match but a partial one to a distant relative, from which investigators build a family tree, narrow to a candidate, and confirm with a separately collected DNA sample. We walk through the mechanics, and a Texas case, in the companion post; here the focus is the law.

The Standing Trap

The single most important, and least appreciated, feature of a genetic genealogy case is a standing problem, and it is worth understanding before anything else about the Fourth Amendment. Fourth Amendment rights are personal. To challenge a search, a defendant has to show that it violated their own reasonable expectation of privacy, not someone else’s.

In a FIGG case, the defendant did not upload anything. When investigators search a consumer database and find a partial match through the profile of the defendant’s second cousin, it is the cousin who shared genetic information with the company, not the defendant. The defendant’s own DNA was never in the database. So the privacy interest that was arguably invaded, if any was, belongs to the relative, and the relative, whose upload just helped solve a crime, has no reason to complain. The defendant, who has every reason, may have no standing to raise it at all. The person with the best claim will not bring it, and the person who would bring it may not have the claim.

That is not a theoretical worry. In State v. Hartman, 534 P.3d 423 (Wash. Ct. App. 2023), the defendant was identified through a GEDmatch search and argued that comparing the crime-scene DNA against his relatives’ profiles invaded his privacy. The court disagreed. It held that there is no privacy interest in the commonly held DNA that a relative voluntarily uploads to a public database that openly allows law enforcement access, and that, lacking a privacy interest of his own, the defendant had no standing to challenge the search. What makes Hartman especially sobering is the law it applied. Washington was not relying on the Fourth Amendment; it was applying Article I, Section 7 of its own constitution, which protects “private affairs” more broadly than the Fourth Amendment does, and it still found no privacy interest to vindicate. A court operating under more protective law reached that result anyway.

The counterintuitive endpoint, as commentators have noted, is that the government can effectively search a large share of the population’s genome by searching the fraction of people who chose to upload to consumer databases, while the relatives swept in, who made no such choice, are the ones with standing to object, and the person actually prosecuted is not.

The Third-Party Doctrine and the Carpenter Argument

Even setting standing aside, there is a live Fourth Amendment question about the search itself. Under the Katz framework, a person has a reasonable expectation of privacy in information they have not exposed to the public. But the third-party doctrine, from Smith v. Maryland (1979) and United States v. Miller (1976), holds that when a person voluntarily hands information to a third party, a bank, a phone company, a business, they assume the risk it will be shared with the government and lose Fourth Amendment protection in it. Applied to FIGG, the argument is that the people who uploaded profiles to GEDmatch or FamilyTreeDNA assumed exactly that risk.

The counterargument runs through Carpenter v. United States (2018), which carved a narrow exception to the third-party doctrine for cell-site location data that was deeply revealing, comprehensive in reach, and effectively unavoidable. Genetic data fits each of those descriptions and adds one the Court did not face: a genome discloses not just its owner but the owner’s relatives, who made no choice to share anything. Whether the assumption-of-risk logic can reach information that implicates people who never assumed any risk is unresolved, and it is the heart of the doctrinal challenge, a challenge the defense raises even knowing the standing problem may keep a court from ever reaching it.

The DOJ Policy and What It Requires

The Department of Justice issued an interim policy on forensic genetic genealogy in 2019. It requires investigating agencies to identify themselves as law enforcement when they upload a profile, limits the technique to violent crimes and unidentified-remains cases, forbids charging anyone on a genealogy lead alone without independent confirmation, and directs investigators to prefer databases that tell their users law enforcement may search them.

The catch is that the DOJ policy is an administrative rule, not a constitutional one. Breaking it does not make the resulting evidence inadmissible; courts have treated a policy violation as no basis for suppression absent an independent constitutional violation. The guidelines create accountability inside the executive branch; they do not create suppression rights for defendants. GEDmatch, after the backlash that followed the Golden State Killer case, moved to an opt-in model in which users must affirmatively agree to law enforcement searches, while FamilyTreeDNA has used an opt-out model. Neither policy has been held to create Fourth Amendment rights, and scholars including Natalie Ram have argued that terms of service between private companies and their users cannot define the constitutional relationship between citizens and the government. It is worth being honest that the argument runs the other way too. Orin Kerr, writing shortly after the Golden State Killer arrest, saw no Fourth Amendment issue at the database-matching stage at all, on the reasoning that the government was simply checking data others had voluntarily made public. So far, his reading has described the case law better than the critics’ has, which is precisely why the defense has to be built on more than the constitutional argument alone.

Decades-Old Evidence: Chain of Custody and the Lab

Most, though not all, of the cases these initiatives target are old, and age creates defense challenges that have nothing to do with the Fourth Amendment.

Sample integrity. Biological evidence stored for decades degrades, and improper storage, temperature swings, humidity, and contamination affect both the sample and any analysis of it. The whole-genome and SNP methods that make FIGG possible are more sensitive than STR testing, but sensitivity cuts both ways: applied to a degraded sample, a sensitive method can amplify artifacts and contaminants alongside the real DNA.

Chain of custody across decades and agencies. Evidence from 1975 may have passed through several agencies, evidence rooms, and storage facilities over fifty years. Every transfer and every custodian is a link the State must establish, and gaps, undocumented periods, reorganized or closed agencies, and lost evidence-room records are legitimate grounds to question whether the sample analyzed today is the sample collected then. When an evidence system fails, the damage runs through hundreds of cases, as the Houston crime lab history in our post on forensic misconduct shows.

The laboratory process itself. Othram’s methods are proprietary. Its Forensic-Grade Genome Sequencing, its database-search protocols, and its family-tree construction are not published for adversarial scrutiny the way long-established methods are, and the validation questions, error rates, the conditions that yield reliable results rather than artifacts, and the bioinformatic pipelines that call variants from raw data are all fair targets. These are the same reliability concerns the 2009 National Academy of Sciences report raised across forensic science, and in Texas a conviction later shown to rest on discredited or unvalidated science can be challenged through the junk-science writ.

The Confrontation Clause and the Analysts

The analysts whose work produces the genetic profile and the genealogical conclusion are witnesses, and their reports are testimonial. Under Melendez-Diaz and Bullcoming, the defense can demand live testimony from the analyst who did the work rather than a certificate or a stand-in. The Supreme Court tightened that rule in Smith v. Arizona (2024), holding that a substitute expert cannot relay an absent analyst’s testimonial statements for their truth without triggering the Confrontation Clause, which closed a common prosecution workaround. We cover Smith and the surrogate-witness problem in our post on probabilistic DNA software. A FIGG match is not self-proving; someone competent has to answer for it under oath.

Confirming the Lead: Abandoned DNA

Because a genealogical lead is not proof, investigators confirm it by obtaining the candidate’s DNA, usually either by court order or by collecting “abandoned” DNA, a discarded cup, a cigarette butt, a swab from a door handle, without the person’s knowledge. Under California v. Greenwood (1988), trash left at the curb is abandoned and unprotected, and courts have generally extended that to discarded biological material. But abandonment is not always clean. DNA taken from a shared surface, or from an object removed without the person’s awareness, or under circumstances where the “abandonment” was anything but voluntary, is a contestable collection, not an automatic one.

What This Means for Texas Defendants

Othram is a Texas company, based in The Woodlands, and Texas agencies already use FIGG in cold cases. The Florida push is a signal of where this is heading, faster and broader, as sequencing gets cheaper and the databases grow. For a Texas defendant identified this way, the landscape is challenging but far from hopeless. The constitutional questions are genuinely open above the trial court, the chain-of-custody problems in decades-old cases are substantial, the Confrontation Clause rights against the laboratory are enforceable, and the abandoned-DNA step that turns a lead into a case is itself open to challenge.

There is one more point, and it is the sharpest Texas angle of all. In 2021, Maryland and Montana became the first states to pass laws restricting law enforcement access to consumer genetic databases, requiring judicial authorization before police can search them, and a few states have since followed. Texas has not. A Texan’s genetic privacy against this technique rests entirely on constitutional arguments that courts have so far been reluctant to accept, with no statute standing behind them. Until that changes, the defense is the argument, and it has to be made by someone who understands both the law and the science.

Deandra Grant holds a Master of Science in Pharmaceutical Science, a Graduate Certificate in Forensic Toxicology, and the ACS-CHAL Forensic Lawyer-Scientist designation, the analytical-chemistry and forensic-methodology credentials that bear directly on the laboratory work behind any genetic evidence, old or new. Deandra Grant Law handles DNA and forensic-evidence challenges in criminal cases throughout North Texas. Call (214) 225-7117 for a free, confidential case review.

This post is general legal information for educational purposes, not legal advice, and it describes a fast-developing area of law. Case citations and policy details should be independently verified against current sources before being relied on in any filing.

Sources and Further Reading

• Office of the Florida Attorney General, news release on the Othram cold-case partnership (2026). myfloridalegal.com
• State v. Hartman, 534 P.3d 423 (Wash. Ct. App. 2023), on standing and genetic genealogy. The Washington Supreme Court denied review on January 2, 2024, which leaves Hartman on the books as published law in that state rather than one panel’s view of it.
• Electronic Frontier Foundation on the 2021 Maryland and Montana statutes, the first laws restricting law-enforcement access to consumer DNA databases. eff.org
• U.S. Department of Justice, Interim Policy on Forensic Genetic Genealogical DNA Analysis and Searching (effective November 1, 2019).
• Natalie Ram, “DNA by the Entirety,” 115 Colum. L. Rev. 873, on genetic data shared among relatives who never consented to its use.
• Related posts in this series: cold-case hair analysis and genetic genealogy, probabilistic DNA software (which covers Smith v. Arizona), forensic misconduct and the Houston crime lab, the 2009 NAS Report, and the Texas junk-science writ.