Junk Science in United States v. Pool

Having granted en banc review in United States v. Pool, 621 F.3d 1213 (9th Cir. 2010), the U.S. Court of Appeals for the Ninth Judicial Circuit could well produce as wild a set of conflicting opinions on DNA databases as it did in United States v. Kincade, 379 F.3d 813 (9th Cir. 2004).

The panel that heard the Pool case divided 2-1. Judge Callahan wrote an opinion upholding the federal law on taking DNA after an arrest but before a conviction that visiting Judge Lucero (of the Tenth Circuit) joined. Judge Lucero also wrote a separate opinion. Judge Schroeder dissented.

The briefs that informed these three opinions left something to be desired. Here, I’ll focus on one of my pet peeves–disingenuous or inane claims about the CODIS STR loci as a threat to privacy.

Appellant’s Opening brief (available from a link on EPIC’s website, along with a one-sided list of vaguely related articles) claims that “DNA profiles derived by STR may yield probabilistic evidence of the contributor’s race or sex.” [1] Probabilistic evidence of sex from autosomal STRs? The arresting officers or jailers need a genetic test for that?

Then the brief cites Simon Cole’s writing to support its sweeping statement that “scientific studies have debunked the notion that these regions of the genetic code are devoid of any biological function.” Yet, the brief cites no study that “debunks” the notion that the length polymorphisms of the CODIS tetranucleotide STRs lack “biological function.” The concurring opinion of Judge Lucero recognizes that Cole rejects the claim of functionality (for the moment). [2] However, a group in France has a theory and some data for a mechanism through which one such STR locus could regulate the expression of an enzyme. [3]

Finally, the brief proposes that the “specter of discrimination and stigma could arise where one or more STRs is found to correlate with another genetic marker whose function is known, so that the presence of the seemingly innocuous STR serves as a ‘flag’ for that genetic predisposition or trait.” [4] As an example of this flag theory, an accompanying footnote states that: “A study in England from 2000 found that one of the markers used in DNA identification is closely related to the gene that codes for insulin, which itself relates to diabetes.” [5]

The accused STR is TH01. It has been used in many studies investigating the association between (a) SNPs, VNTRs, and this STR in a complex of genes and (b) a large number of diseases. Unsurprisingly, associations have been observed. Some of the reported associations were spurious and were not replicated. Other associations probably are real. This does not mean that TH01, by itself, is a useful predictor of any of these diseases in a given population. In fact, one forensic biologist used the 2000 paper cited in Pool’s brief to show that “such associations [between forensic STRs and disease-causing alleles in genes] are so ridiculously weak that serious protest could never form.” [6] His explanation follows:

This is illustrated well by the possible association between certain alleles of an STR named TH01 and diabetes type 1 (Bennett and Todd, 1996; Stead et al., 2000). TH01 alleles are used routinely in DNA typing, and for a minute, the manufacturers of genetic fingerprint kits started to feel the heat over the possible association between an exonic illness and an intronic allele. Fortunately, it takes just a pen and a piece of paper to brush off possible concerns: four out of 1000 Europeans will eventually get diabetes type 1. If you carry one of the ‘risk’ alleles in the intronic TH01 region, your chances of getting diabetes type 1 is 0.13 out of 1000. If I find out that you are carrying the alleged risk allele in my laboratory during DNA typing, I could–but I am not allowed to–calculate your total risk for diabetes as 0.4 � 1.3 = 0.52%. In plain language: in the worst case scenario, one allele of your possible genetic fingerprint might tell me that your general risk of getting diabetes type 1 is increased from 0.4 to 0.52%. All other alleles will not tell me anything about you, or your potential risk for illnesses. Abuse of such information is impossible because it simply has no practical predictive value.

I do not want to “brush off possible concerns,” and I understand the pressures and temptations of advocacy. Still, I wonder whether the Sacramento Federal Defender consulted the scientific literature on TH01 before citing an old study. Or whether he knew that the claims in the law review essay cited in the brief were the subject of an extensive rejoinder in the same journal. [7] If he did, he choose not to share this fact with the court. To my mind, that is not good advocacy.


1. Brief at 12 (quoting from a plurality opinion in Kincade).
2. 621 F.3d at 1230.
3. See Rolando Meloni, Post-genomic Era and Gene Discovery for Psychiatric Diseases: There Is a New Art of the Trade? The Example of the HUMTH01 Microsatellite in the Tyrosine Hydroxylase Gene, 26 Molecular Neurobiology 389 (2001).
4. Brief at 12
5. Id. at 12 n.8.
6. Mark Benecke, Coding orNon-coding?, That Is the Question, 3 European Molecular Biology Organization Reports 498 (2002).
7. David H. Kaye, Please, Let’s Bury the Junk: The CODIS Loci and the Revelation of Private Information, 102 Nw. U. L. Rev. Colloquy 70 (2007).