Tag Archives: New York Times

Good Point, Bad Math: DNA Database Statistics Misunderstood (Again)

An op-ed article in yesterday’s New York Times speaks of DNA database hits as “high risk.” That police, prosecutors, defense lawyers, and juries should not accept every hit as conclusive proof of guilt is quite true. To prove the point, the article calls attention to a false arrest in the ongoing California case of the murder of millionaire investor Raveesh Kumra — a matter that made the news last month. Although the facts of the case are atypical, it is a warning to overly credulous police and prosecutors.

The article, by Hastings Law Professor Osagie K. Obasogie, also rehashes two dated — and previously refuted (or so I think) incidents — that are supposed to show that DNA databases are producing lots of false hits. Some of the factual and statistical errors in the article are identified in the Forensic Science, Statistics, and the Law Blog (http://for-sci-law-now.blogspot.com/2013/07/good-point-bad-math-dna-database.html).

On the “Clear” Outcome Under “Established” Law

Today’s New York Times included an editorial (California and the Fourth Amendment) on Haskell v. Harris, the challenge to the California Proposition requiring DNA sampling on arrest. En banc oral argument takes place today. The following is a letter I sent to the Times editor. I expect somewhere between 0 and 50 percent of it to be published there (point estimate = 0):

Dear Editor,

Your editorial (September 19) asserts that the constitutionality of taking DNA on arrest “should be clear” given “established rights against unreasonable search and seizure.” Yet, over vigorous dissents, federal courts of appeals have ruled otherwise–twice in panels of the Ninth Circuit and once (en banc) in the Third Circuit.

Whether acquiring purely biometric data from arrestees necessitates a warrant is doubtful, and whether acquiring DNA data is “unreasonable” is a close question. The physical invasion of personal security is minor when the individual is already in custody and the sampling is only marginally more intrusive than fingerprinting. The medical information content of the identification profile is (given current knowledge) only slightly more significant than that of a fingerprint. Very few false convictions arising from DNA database searches have been documented. (One in Australia has been reported.)

Contrary to the suggestion in the editorial, what divided the judges in the Ninth Circuit was not whether “the law’s real purpose was investigation.” No one doubted that. The dissenting judge believed that the Supreme Court already had decided that “fingerprints may not be taken from an arrestee solely for an investigative purpose, absent a warrant or reasonable suspicion that the fingerprints would help solve the crime for which he was taken into custody.” What the Court actually held was “that transportation to and investigative detention at the station house without probable cause or judicial authorization together violate the Fourth Amendment.” The dissenting judge also worried, among other things, that “it is possible that … at some future time,” an identification profile might permit strong inferences about the diseases an arrestee has or might develop.

I do not claim that arrestee DNA sampling clearly is constitutional. There are a number of valid concerns about indefinite sample retention and other matters. Neither do I maintain that its benefits (which are not well quantified) plainly outweigh its costs and its impact on legitimate interests in personal privacy and security. But assertions that the balance is “clear” and that the “established” law dictates the result oversimplify a delicate constitutional question.