Tag Archives: databases

“Human Error, Bias, and Malfeasance” in DNA Databases and Law Reviews

A new article in the Boston University Law Review offers the following warning:

[E]xpansive police arrest authority–and the desire to continually enlarge identity evidence databases at very little cost in time and expense–should give pause for several reasons. First, contrary to common public perception, DNA is not infallible. Rather, like other evidence, it is subject to human error, bias, and malfeasance, and has figured in several wrongful accusations and convictions. As Professor David Kaye notes in his recent book:

How probable is it that two, correctly identified DNA genotypes would be the same if they originated from two unrelated individuals? By definition, [such matches] do not consider any uncertainty about the origins of the samples (the chain-of-custody issue), about the relatedness of the individuals who left or contributed the samples (the identical-alleles-by-descent issue), or about the determination of the genotypes themselves (the laboratory-error issue).

Wayne A. Logan, Policing Identity, 92 B.U. L. Rev. 1561, 1580-89 (2012) (footnote numbers omitted).

Having searched without success for a single case in the U.S. of a false conviction based on DNA evidence from a database search,1 I was puzzled. Could I have missed several false convictions arising from erroneous DNA testing? Did these cases involve database trawls, where observer “bias” is not normally an issue?

Being a lawyer, I did what any reader of law review articles must do. I turned to the footnotes. The footnote on false convictions as a reason to constrain DNA databases reads as follows:

See Greg Hampikian et al., The Genetics of Innocence: Analysis of 194 DNA Exonerations, 12 Ann. Rev. Genomics & Hum. Genetics 97, 107 (2011) (mentioning existence of at least fifteen exonerations in which DNA resulted in conviction).

If Professor Logan (and the source-citation reviewers of the Boston University Law Review) are correct, Professor Hampikian discovered at least 15 cases of DNA evidence that resulted in false convictions. How could I have missed all these case in my earlier postings?

The Genomics and Human Genetics review article plainly does not even begin to support the claim that DNA testing produced 15 false convictions. It merely states that among previously analyzed cases of postconviction exonerations, “there were at least 15 cases where DNA was tested prior to conviction.” Hampikian et al., supra, at 107. Let’s look at the outcomes of this DNA testing, as presented by Dr. Hampikian and his colleagues:

  • The cited article does not even discuss the outcome of the DNA tests in two of the 15 cases because there were no “transcripts or other accurate information on the DNA results available.” Id. Counting two cases on which there is no information as showing that contemporary DNA databases produce false convictions is surprising.
  • “The majority of these cases included proper testimony, with DNA results that excluded the exoneree (9 of the 13 cases). These exclusions were explained away by the state in various ways–perhaps the defendant had an unknown codefendant, the DNA could have come from a consensual sex partner, etc.” Id. Claiming that DNA databases should be constrained because most DNA typing accurately showed that a defendant was not the source of an incriminating sample is inane.
  • “In 5 of the 13 cases, DQ alpha tests included the exonerees as possible contributors. In 4 of these 5 cases, however, more discriminating tests performed postconviction excluded the exonerees. In the remaining case, a second round of DQ alpha testing exonerated the defendant after it was discovered that the original lab analysis was incorrect.” Id. Before the DQA test was retired from forensic DNA testing, it was known to be relatively undiscriminating. See, e.g., Cecelia A. Crouse, Analysis of HLA DQ alpha Allele and Genotype Frequencies in Populations from Florida, 39 J. Forensic Sci. 731 (1994); NFSTC, DNA Analyst Training. Questioning databases stocked with CODIS profiles because a different, bi-allelic locus has different properties is silly.
  • “There were four cases where improper DNA testimony was given at trial. In one, the analyst testified about a match based on DQ alpha testing; however, the analyst did not disclose that it was only a partial match. In another case, the analyst did not provide the proper statistic for the population included by the results of DQ alpha testing.” To be sure, “improper” testimony is deplorable, but it is not clear that the analyst in the first case incorrectly stated the implications of the match or, more importantly for worries about databases, that analysts working with database matches would give incorrect estimates of genotype frequencies.
  • “In a third case, the analyst testified that the DNA matched the exoneree, but failed to disclose an additional exclusionary DNA result.” Withholding exculpatory evidence of any sort–DNA, fingerprint, toolmark, eyewitness, or anything else–is unconscionable and unconstitutional. But it is not much of an argument against inclusive DNA databases.
  • “In the final case, the analyst misinterpreted the results of the testing (which was performed incorrectly–failing to separate the male and female DNA during differential extraction), falsely including the exoneree as a source of the DNA when in fact he should have been excluded.” Yes, if crime-scene DNA is mistyped, and if this error goes unnoticed, a database match could result.

Can DNA databases produce false convictions? Of course they can. Police can commit perjury about DNA evidence, just as they can about other evidence. If there were no databases, it might be slightly harder to fabricate such impressive evidence. DNA evidence, like all evidence, “is subject to human error, bias, and malfeasance.” So are law review articles. (And so are blog postings–corrections are welcome).


1. David. H. Kaye, Have DNA Databases Produced False Convictions?, Forensic Science, Statistics, and the Law, July 7, 2012 (cross-posted to The Double Helix Law Blog); David H. Kaye, Genetic Justice: Potential and Real, Forensic Science, Statistics, and the Law, , June 5, 2011 (cross-posted to The Double Helix Law Blog).

Cross-posted to Forensic Science, Statistics, and the Law.

The Dictionary and the Database: Thoughts on State v. Emerson

Last week, the Supreme Court of Ohio held that the state may use, in a completely unrelated case, information derived from a DNA sample acquired pursuant to a search warrant without seeking a new warrant. This result is not novel–indeed, a contrary outcome would have departed from the law elsewhere.

Nevertheless, the opinion in State v. Emerson presents a new wrinkle. After Dajuan Emerson was acquitted of the 2005 rape of a 7-year-old girl, his DNA profile somehow resided in the state’s convicted-offender database. Then, in 2007, 37-year-old Marnie Macon was stabbed 74 times in her apartment. (Ludlow 2012). Police recovered blood from a door handle. The DNA profile from this crime-scene sample (often called a “forensic sample”) was run against the state database. It matched Emerson’s profile from 2005. After the trial court denied a motion to suppress this match, the case went to trial and the jury found Emerson guilty of aggravated murder (and tampering with evidence). An Ohio District Court of Appeals affirmed, and the state supreme court affirmed that judgment.

The obvious questions are why the 2005 profile entered the convicted-offender database and whether the Fourth Amendment’s exclusionary rule for unreasonable searches or seizures applies to the resulting cold hit. The Ohio Supreme Court’s analysis of these issues is a little odd. I shall quickly run through the opinion, indicating the oddities.

What is an allele?

The first peculiarity is ultimately of no moment, but I’ll mention it anyway because it shows the continuing inability of too many judges (or the recent law school graduates who are their clerks) to consult suitable scientific references. According to the opinion, “[a] DNA profile consists of a series of numbers that represent different alleles that are present at different locations on the DNA” and “[a]n allele is defined as ‘either of a pair of genes located at the same position on both members of a pair of chromosomes and conveying characters [sic] that are inherited in accordance with Mendelain [sic] law.’ Webster’s New World Dictionary, Third College Edition 36 (1988).”

The alleles used in modern DNA databases are not parts of genes. (Well, some of them are meaningless variations within introns, but even those do not “convey characters” as the classical definition from Webster’s would require.) Perhaps judges should not be criticized for thinking that the word “allele” always refers to genes. To denote variations in DNA sequences that are not the allelotypes of genes, forensic scientists themselves borrowed from the terminology for genes, inviting such confusion. (Kaye 2010). But there are many reasonably accurate explanations of forensic STR “alleles” in the legal and forensic science literature. Consequently, there is little excuse using the inapt dictionary definition. Fortunately, this error does not affect anything else in the opinion.

How did Emerson’s DNA profile get into a CODIS database?

The justices evinced little concern about the statutory violation that led to the fateful match in the case. In fact, the unanimous opinion prominently denies that putting the profile of someone who was not convicted into the state and national databases (SDIS and NDIS) for future trawls departed from Ohio’s convicted-offender law.

The court reached this counter-intuitive result by relying on Black’s Law Dictionary:

Appellant is correct that R.C. 2901.07 does not support the inclusion of his profile in CODIS. However, the same cannot be said for R.C. 109.573. The superintendent of BCI is empowered to “establish and maintain a DNA database.” R.C. 109.573(B)(1)(b). “DNA database” is defined in part as “a collection of DNA records from forensic casework.” R.C. 109.573(A)(3). “Forensic” is defined as “[u]sed in or suitable to courts of law or public debate.” Black’s Law Dictionary 721 (9th Ed.2009). In this case, the police lawfully obtained the DNA sample in the course of the 2005 rape investigation. Therefore, the profile obtained from the sample is a record from forensic casework and is properly maintained in CODIS. Moreover, we note that neither R.C. 109.573 nor 2901.07 require that the state, on its own initiative, remove the DNA profile of a person who was acquitted at trial.

Again, the failure to consult relevant sources for the actual terminology in the field is a gross mistake. Ohio Revised Code � 109.573(3) defines “DNA database” as

a collection of DNA records from forensic casework or from crime scenes, specimens from anonymous and unidentified sources, and records collected pursuant to sections 2152.74 and 2901.07 of the Revised Code and a population statistics database for determining the frequency of occurrence of characteristics in DNA records.

(This is the current version. I am assuming the words are the same as they were in 2007.) The “records collected” under the enumerated sections pertained to “adjudicated delinquents” and to convicted offenders–not to mere suspects. The phrase “forensic casework or crime-scene samples” refers to DNA of unknown origin–from vaginal swabs, clothing, property, etc. As the FBI explains, “the DNA data that may be maintained at NDIS [consists of profiles from] convicted offender, arrestees, legal, detainees, forensic (casework), unidentified human remains, missing persons and relatives of missing persons.” (FBI, undated). There is no authorized category for sundry individuals whose DNA profiles have become known to the police for miscellaneous reasons. Ohio did not take DNA samples from arrestees or detainees until 2011. Under the Emerson court’s peculiar reading of the statute, police in Ohio could use the “abandoned DNA” ploy to acquire a profile from a person even without a warrant and upload it to the state and national databases.

The court’s theory that the Ohio legislature used the phrase “forensic casework” to cover every sample and profile “[u]sed in or suitable to courts of law or public debate” is astonishing. A convicted-offender database system has one set of so-called “forensic” profiles (that could link perpetrators to crimes) and another set of convicted-offender profiles (who might be found to be the perpetrators of the unsolved solves). The “forensic” profiles come from the unknown perpetrators of the crimes. They can be matched, if possible, against the convicted offenders’ profiles (and among one another to identify serial crimes). Neither they nor the convicted-offender database was intended to house profiles from specific suspects who never were found guilty of a qualifying crime. Thus, the state had no convincing legal basis for uploading Emerson’s profile to SDIS and NDIS–and the court should not have approved of such misconduct.

Nonetheless, the statutory violation does not justify excluding the cold hit under the Fourth Amendment. The U.S. Supreme Court has not been kind to the exclusionary rule in recent years. As Emerson observes, it has held that a violation of a state statute does not make a search constitutionally unreasonable.

Did Emerson lack standing to complain of a Fourth Amendment violation?

The Emerson opinion contains a third error. The court holds “that a person does not have standing to object to the retention of his or her DNA profile or to the profile’s use in a subsequent criminal investigation.” This misrepresents the meaning of “standing.” In the Fourth Amendment context, the standing requirement bars “attempts to vicariously assert violations of the Fourth Amendment rights of others.” United States v. Salvucci, 448 U.S. 83, 86 (1980). Thus, in Salvucci, police searched an apartment rented by a defendant’s mother and found checks that her son had stolen from the mails. In his prosecution for possession of stolen mail, the son lacked standing to complain the search violated the mother’s interest in the privacy of her apartment.

In Emerson, the defendant never argued that the cold hit violated someone else’s rights. He argued that it violated his right to be free from unreasonable searches because he had a legitimate expectation of privacy in his DNA profile retained by the state. He surely had standing to raise that claim, and the court references to “standing” are superfluous and confused.

Was the retention of the profile and the trawl of the database a search or seizure?

At last, we come to the dispositive issue in the case–was any Fourth Amendment interest of Emerson’s violated by the retention of his profile and the trawl of the database? The court held–correctly, I believe–that Emerson had no such interest. The state acquired the DNA sample in 2005 pursuant to a search warrant of unchallenged validity. Laboratory analysis of the sample was not a separate search, but the very reason for the search warrant. Simply keeping the identifying profile and looking to see whether it matched new profiles in the “forensic index,” as the FBI calls them, does not rise to the level of new search. Once the government legitimately acquires information pursuant to a search warrant, it need not toss out and forget about that information if it cannot secure a conviction. In later investigations and prosecutions, it can use what it finds in the fully authorized and entirely legitimate search.

Obviously, the situation would be otherwise if the original search were unreasonable. Then the evidence should be excluded to vindicate the defendant’s right to be free from unreasonable searches and seizures. But it would be worse than pointless to exclude, on constitutional grounds, legitimately acquired evidence of guilt. This is the sound core of the reasoning in Emerson. Whether the defendant was acquitted in the case that generated the search warrant, whether  he was convicted then, or whether he never was prosecuted in that case makes no difference. There is no constitutional reason to exclude evidence from a reasonable search.

In Boroian v. Mueller, a case that Emerson overlooks, the U.S. Court of Appeals for the First Circuit held that continued trawls of a database may continue even after an offender has completed his sentence. Emerson extends the reasoning of Boroian to an individual whose DNA profile should not have been in the database in the first place. But because the objection in that respect is entirely statutory, it does not change the result.

Of course, one can question the conclusion that trawling a database is not a separate search, and some commentators as well as some recent opinions on the constitutional of pre-conviction DNA sampling, analysis, and trawling have spoken of different steps in the process as if they were independent searches, each of constitutional magnitude. For reasons stated in Kaye (2011), however, I doubt that these claims are tenable. Despite the terminological and conceptual flaws in the opinion in Emerson, the Ohio Supreme Court reached the correct result.


United States v. Salvucci, 448 U.S. 83, 86 (1980)

Boroian v. Mueller, 616 F.3d 60 (1st Cir. 2010)

State v. Emerson, No. 2011-0486 (Ohio Nov. 1, 2012) (Slip Opinion No. 2012-Ohio-5047)

FBI, Frequently Asked Questions (FAQs) on the CODIS Program and the National DNA Index System, http://www.fbi.gov/about-us/lab/codis/codis-and-ndis-fact-sheet.

David H. Kaye, The Double Helix and the Law of Evidence (2010)

David H. Kaye, DNA Database Trawls and the Definition of a Search in Boroian v. Mueller, 97 Va. L. Rev. in Brief 41 (2011)

Randy Ludlow, Ohio Suspects’ DNA Can Be Saved for Later Cases, Court Rules, Columbus Dispatch, Nov. 6, 2012

Cross-posted to Forensic Science, Statistics, and the Law.

Genetic Geneology: Is Sarah Yarborough’s Killer a Mayflower Descendant?

In The Double Helix and the Law of Evidence, I remarked that “[s]urname prediction is a concept that has yet to be implemented in forensic science . . . ” (1, p. 211). Now, cold-case detectives investigating the 1991 rape and strangulation of a 16-year old girl in Seattle are looking for “a distant relative of Edward and Samuel Fuller, who crossed the Atlantic on the Mayflower in 1620 [and who] might even share their last name” (2).

Sarah Yarborough left home to take part in a dance-team competition one morning in December. She never returned. Six people had seen a man in his 20s, with shoulder-length blond hair, a trench coat and dark pants speaking with her or leaving a brushy area where her body was found. In the succeeding months, more than 3,000 tips poured in. DNA analysis excluded some suspects, but trawling offender DNA databases for an exact match produced no leads, and the killer remains unidentified.

Yet, other databases can be searched. “Genetic geneology databases” (3, p. 384) that use Y-STR haplotypes of interest in anthropology are growing in popularity, and some are available on the web. At the suggestion of a scientist at the state crime laboratory, police turned to Identifinders of Huntington Beach, California. Presumably, the firm combed through the online databases to arrive at its conclusion that “there’s a good chance the killer’s last name is or was Fuller” (4) because “the killer is a descendant of Robert Fuller, who arrived in Salem, Mass., in 1630. Fuller was not himself on the Mayflower, but he was related to three passengers: Edward Fuller, as well as Edward Fuller’s brother, Samuel, and 12-year-old son” (2).

The value (and accuracy) of this surmise remains to be seen. None of the tips the police received involve a Fuller (2), and many Fullers had nothing to do with that historic voyage. Moreover, the Mayflower Fullers may be multitudinous. After all, “there are tens of millions of people descended from the 102 passengers and about 25 crew members who arrived on the Mayflower . . .” (2).

Acknowledgment: Thanks to Gene Johnson for telling me about the Yarborough case.


  1. David H. Kaye, The Double Helix and the Law of Evidence (2010).
  2. Gene Johnson, Awkward Twist over DNA Link in Teen’s Slaying, Seattle Times, Jan. 12, 2012
  3. John M. Butler, Advanced Topics in Forensic DNA Typing: Methodology (2011).
  4. Gene Johnson, Mayflower Relative Sought in ’91 Wash. Killing, Seattle Post-Intelligencer, Jan. 11, 2012

Cross-posted to Forensic Science, Statistics, and the Law