Forensic techniques are subject to human bias, lack standards, panel found

In Hollywood, the moment the good guys trace a hair, a bullet fragment or a fingerprint, it’s game over. The bad guy is locked up.

But the glamorized portrait is not so simple in real life.

Graphic

Convictions linked to FBI lab’s flawed forensics

How accurate is forensic analysis?

Learn more about the reliability of each type of forensic analysis.

DNA

Fingerprint

Handwriting

Polygraph

Firearm evidence

Hair and
fiber

Pattern and impression

Bullet lead composition

More on this Story

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• Convicted defendants left uninformed of forensic flaws found by Justice Dept.
• For D.C. man, 28 years lost

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• Photos: Investigating flaws in forensics
• Graphic: Different techniques and their reliability
• Database: Cases affected by bad testimony

Far from infallible, expert comparisons of hair, handwriting, marks made by firearms on bullets, and patterns such as bite marks and shoe and tire prints are in some ways unscientific and subject to human bias, a National Academy of Sciences panel chartered by Congress found. Other techniques, such as in bullet-lead analysis and arson investigation, survived for decades despite poorly regulated practices and a lack of scientific method.

Even fingerprint identification is partly a subjective exercise that lacks research into the role of unconscious bias or even its error rate, the panel’s 328-page report said.

“The forensic science system, encompassing both research and practice, has serious problems that can only be addressed by a national commitment to overhaul the current structure,” the panel concluded in 2009.

Now, Congress and the Obama administration are trying to regulate forensic science to help establish standards. Senate Judiciary Committee Chairman Patrick J. Leahy (D-Vt.) and Commerce, Science and Transportation Committee Chairman John D. Rockefeller IV (D-W.Va.) are weighing legislation that could subject techniques to greater scientific scrutiny and help establish their ranges of accuracy.

A Leahy bill would create a new office of forensic science in the Justice Department. Rockefeller is preparing legislation to expand the role of the National Science Foundation and the National Institute of Standards and Technology in setting scientific standards and research goals.

The Obama administration is also looking to “strengthen the linkage between cutting-edge science . . . and the forensic tests used by law enforcement,” said Rick Weiss, spokesman for the White House Office of Science and Technology Policy.

Police and law enforcement agencies have rebuffed recommendations to remove crime labs from their control.

Since 2002, failures have been reported at about 30 federal, state and local crime labs serving the FBI, the Army and eight of the nation’s 20 largest cities.

Advances in DNA testing are exposing errors at unexpected rates. In November, researchers with the Urban Institute reported that new DNA testing appeared to clear convicted defendants in 16 percent of Virginia criminal convictions between 1973 and 1988 in which evidence was available for retesting.

A 2009 study of post-conviction DNA exonerations — now up to 289 nationwide — found invalid testimony in more than half the cases.

“There are just too many related problems for this to be dealt with ad hoc,” said Brandon L. Garrett, a professor at the University of Virginia School of Law.

More DNA testing alone is not the answer, experts say. Biological evidence historically is collected in fewer than 20 percent of criminal cases. Other questioned forensic techniques are used far more often, with mistakes harming defendants and crime victims whose true assailants remain at large.