55With forensic evidence -- fingerprints, DNA, ballistics, bloodstain patterns, footwear analysis and the like -- a significant factor in more and more verdicts, let's hope Judge Swan Yerger's recent action sets a national precedent. Let us explain why.

But research indicates that forensic evidence is often flawed. So, in fairness, defendants should have a right to forensic expertise, just as they have a right to an attorney.

Consider DNA profiling. A 2007 University of California study found that "DNA tests sometimes produce ambiguous results that are subject to multiple interpretations," thus introducing "subjective judgments" to the process. This may happen, for example, when the recovered DNA of criminals and their victims are mixed together, a frequent occurrence. In such cases DNA analysts typically have a suspect's DNA profile before them to help sort out the evidence "correctly." In other words, they go into to the test with a cheat sheet, sort of like a criminal lineup in which a potential witness is told, "Number 4 is our suspect, does he look familiar?"

Some mistakes in DNA profiling have been discovered. Josiah Sutton, for example, spent more than four years in jail after being convicted of rape at the age of 16, largely on the basis of a DNA test that was later discredited. No one knows how many similar mistakes go undiscovered.

Given that DNA profiling is widely acclaimed as the "gold standard" of forensic science, it is not surprising that even greater problems exist in other areas of forensics.

A comprehensive study of crime lab proficiency published by the Journal of Forensic Sciences in 1995, the most recent study of its kind, found incorrect matches between recovered evidence and reference samples more than 10 percent of the time in areas such as fibers, paints, glass and body fluid mixtures.

The rate of errors in real casework might be higher, since crime labs are probably most careful to screen out "false positives" when they know they are being tested themselves. The same study suggested a false positive rate of 2 percent for fingerprints, creating the potential for thousands of false convictions each year.

To make the forensic science used in American courts more reliable, efficient and fair, several changes are needed. For example, crime labs should be independent, not under the umbrella of law enforcement agencies. Despite everyone's best intentions, when crime labs work for the prosecution there is pressure to produce the incriminating evidence the police and prosecution need. Independent crime labs would be free of this potentially unhealthy influence.

In Gideon v. Wainwright, the Supreme Court recognized that our Sixth Amendment right to a fair trial includes the right to legal counsel. Today, we have no similar right to forensic expertise, though forensic scientists are often more important to case outcomes than defense lawyers. When crime labs work for the prosecution and an indigent defendant has no scientist to help him, the process lacks fundamental fairness.

The right to forensic expertise also would create the kind of checks and balances that will improve forensics. Here is how: In most criminal cases one side or the other will want the forensic evidence reviewed.

That side will have an incentive to document forensic science's shortcomings and bring them to the attention of the court whenever it is strategically appropriate. Slowly, case by case, the system will improve.

• Roger Koppl is a research fellow at The Independent Institute, Oakland, Calif., and director of the Institute for Forensic Science Administration at Fairleigh Dickinson University, Madison, N.J. Dan Krane is a professor of biological sciences at Wright State University on Dayton, Ohio. Readers may send e-mail to Koppl at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it and to Krane at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it For information on TII's funding, please go to http://www.mediatransparency.org/recipientgrants.php?recipientID1119.