It is crucial to have a defense expert who can offer an opinion when a case turns on a critical matter that has an opinion offered by a state expert. This is true for a variety of common sense reasons confirmed by experience. It has been especially highlighted in a recent book that looks at high profile cases which used FBI examiners with distressing results.

Attorneys are not experts in the forensic sciences and we cannot expect them to be experts. Forensic experts spend years learning their field. Attorneys do not and cannot spend years learning the field of expertise to be able to check the reliability of the testing done by the state experts, to be able alone to effectively cross the state's expert on the testing done and the opinions rendered.

The defense attorney is ethically obligated to determine the state's expert analysis of critical evidence was properly done but are we meeting our obligation? Not according to some significant commentators. "There are several legal obstacles to rooting out bad forensic science. The first is the lawyers themselves. Few are prepared to orchestrate a defense around a scientific subject or technology they know little about; even fewer are prepared to spend the hours or weeks it may take to prepare. The vast majority of law schools still offer no specific courses devoted to scientific opinion or expert witness testimony." John F. Kelly, Phillip K. Wearne, Tainting Evidence: Inside the Scandals at the FBI Crime Lab (1998).

Experts Make Mistakes, Misjudgments. It is not surprising that the many laboratories with examiners of various training and experience produce some results which are not accurate, valid or reliable. The studies done over the last quarter of century confirm that mistakes and misjudgments are made by some experts. A quick look at 3 studies reveals the limits of relying on tests without any scrutiny of them.

In 1974 the Forensic Science Foundation issued a series of 21 tests for a range of evidence types to some forensic laboratories. These showed unacceptable proficiency in:

• Identifying animal hair specimens;
• Determining paint, soil, glass, blood, handwriting samples shared a common origin.

Labs also lacked analysis techniques for discriminating bloodstains. Analysis of these findings identified the following causes of the inadequacies:

• Misinterpretation of test results;
• Examiners who were careless or lacked training or experience;
• Mislabeled or contaminated standards;
• Inadequate data bases; and,
• Faulty testing procedures.

There was testing of controlled substances, hair, flammables, explosives fibers, blood and body fluids. There were misidentifications or failure to accurately identify in each of those areas.

Joseph L. Peterson, D.Crim. and Penelope N. Markham, Ph.D. in Crime Laboratory Proficiency Testing Results, 1978-1991, II: Resolving Questions of Common Origin, Journal of Forensic Sciences, Vol. 40, No. 6 (Nov. 1995) at 1009 reviewed the ability of laboratories to determine if an unknown sample shared a common origin with a known sample. The evidence examined at was firearms, toolmarks, hair, footware, physiological fluids, glass, paint, fibers, latent fingerprints, questioned documents and metals.

Error rates ranged from .5% for latent print cards to a high of 23% for automotive parts as demonstrated by the following table:
 

Id. At 1010.

Experts Render Bad Opinions in some circumstances due to incompetence, perjury and falsification.

Fred Zain was a chemist for the West Virginia police crime lab who testified in many cases about tests he never actually did. Tainting Evidence tells us about Fred Zain, Texas pathologist Ralph Erdmann, Mississippi forensic dentist Michael West,. FBI special Agent Thomas Curran, a serologist and others. These experts did such things as falsify evidence, faked autopsies, falsified toxicology and blood reports, did not have the claimed degrees, and committed perjury.

Laura Frank and John Hanchette in a July 19, 1994 story in Gannett News Service’s USA Today entitled "Convicted on False Evidence?: False Science Often Sways Juries, Judges" found 85 cases since 1974 in which prosecutors intentionally or unintentionally used tainted evidence. In the article Roy Taylor, a forensic pathology expert and attorney, said," the public perception is that faking science is rare. The truth is it happens all the time."

Tainting Evidence details information about the FBI that gives a person interested in the reliability of opinions offered by prosecution experts pause:

• Physical evidence not properly examined;
• Failure to file and maintain critical notes;
• Unchecked work done by incompetent examiner;
• DNA typing science and research that has fundamental flaws;
• Failing to take sufficient precautions against contamination;
• Disposing of pivotal evidence;
• Failing to follow protocols;
• Destroying computer drawing that implicated an FBI sniper in a fatal shooting.

When there is a lot at stake for an accused citizen and the state has experts helping it make its case, defense attorneys are increasingly seeking the assistance of defense experts to make sure the judgments are not improperly tainted by prosecutorial bias, testing is competently done, and jurors here both sides of the story.