With lives on the line, old standards must be questioned.

Are fingerprints reliable?

By Katherine Ramsland

In a 1999 murder case, criminalists compared a print of the accused’s ear to an earprint from the crime scene and pronounced him a "likely source." An expert assured the court of the scientific validity of earprint analysis, and the suspect was convicted.

Yet an appeals court reexamined the "science" and overturned the conviction. This action angered earprint experts, who claimed that ears are unique and that earprints should carry as much evidential weight as other matches based on unique comparison. Fingerprints, for example

While the two techniques aren't really equivalent, fingerprint interpretation is getting another look as well. Although fingerprint evidence has been admissible in American courts for nearly a century, one judge is asking some hard questions. His decision may have a significant impact on the future of forensic testimony ‑ even in areas like ballistics and handwriting comparison. And that may be a good thing.

For many years, the operative standard was that of Frye v. United States (1.923), in which the court was asked to rule on the admissibility of evidence from a device that measured blood pressure in people who were telling lies. The court in Frye decided that to be admissible, a scientific claim must be "sufficiently established to have gained general acceptance in the particular field in which it belongs."

On Jan. 7 in a pretrial ruling for a multiple murder case, Judge Louis H. Pollak, a senior federal judge in the Eastern District Court of Pennsylvania, entertained a motion to evaluate fingerprint evidence against U.S. Supreme Court standards set in 1993 and he found such evidence wanting.

The Supreme Court case was Daubert V. Merrell Dow Pharmaceuticals. The resulting standards gave judges guidelines by which they could bar "Junk science" from the courtroom. The court ruled that when scientific evidence is presented, judges must determine whether the method is testable, whether its potential error rate is known, whether the evidence has been peer‑reviewed, and whether it is relevant to the case. In many states, the Daubert standards have replaced those of Frye.

Judge Pollak found that fingerprint evidence failed Daubert on three points. The error rate has not been quantified; the "peers" who review the evidence are not scientists, and the millions of prints on record have never been analyzed for possible duplication.

James Stars, a law professor at George Washington University, testified in an earlier case that became relevant for this hearing. He has long noted the problems of admissibility, particularly with partial ‑or smudged prints:

"There is no scientific basis for fingerprinting as it is presently utilized," he said. "[Fingerprint experts) haven't developed a factual basis for the assertions they make."

To prove similarity between two prints, analysis compares the overall pattern, ridge details, and ridge interruptions. While a "match" admittedly depends on interpretation, the scientific basis rests on two premises:

(1) The friction ridge details of the epidermis on the palm side of the band remain unchanged over one's lifetime, and

(2) These details exhibit sufficient variety that no two people will have exactly the same pattern.

The first premise has been established, but the second is supported ‑ so far ‑ only by the fact that no one as yet has discovered people with duplicate fingerprints.

Pollak’s ruling focused on whether latent prints (the kind picked up at a crime scene), which generally are partial, could be accurately matched to inked prints, which are complete. In a 49‑page opinion, he discussed the lack of scientific standards controlling the technique.

He’ll still allow experts to show in court how comparisons are made and even to say that no two people have the same print. They may not, however, declare that a specific latent print was made by a specific person.

The point seems to be that until fingerprint interpretation becomes a proven science, juries should decide the ultimate issue. While prosecutors may feel it's the expert's judgment that makes the case, it can just as easily carry too much weight.

We should remember that the law often determines people's fates. We have high standards for evidence to ensure due process. It's time now for proponents of fingerprint analysis to subject their field to more rigorous scientific scrutiny. If that field gathers enough scientific support, it once again will be fully admissible in court If it does not, then fingerprint evidence should not carry the weight it now carries in. criminal cases.

Wednesday, February 6, 2002 THE PHILADELPHIA INQUIRER