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Univ. of San Diego School of Law

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Wednesday, March 9, 2005

FBI's Chemical Bullet Lead Analysis Challenged

On Monday, a New Jersey appeals court overturned a murder conviction and ruled that the FBI crime lab's chemical bullet lead analysis ("CBLA") used to connect the bullets to the defendant is based on "erroneous scientific foundations."  Since 1980, this technique has been used in about 2,500 cases and mentioned in court testimony about 500 times.  The technique, known as "chaining," compares the chemical composition of a series of bullets' lead content.  For example, (as reported by the Associated Press), if analysts "find that bullet A is like bullet B and B is like C and C is like D and so on, they then conclude that A is the same as E because they are part of the same chain."  The National Academy of Sciences, a private organization chartered by Congress, has publicly questioned the technique in a report last year, but William Tobin, a retired FBI metallurgist, was the first to doubt its scientific validity.  He submitted testimony in William Behn's case, whose conviction was overturned on Monday.  Chaining was used to link bullets found at Behn's house to bullets found at the crime scene; this expert testimony was the only expert testimony not countered by Behn's defense, and the court wouldn't allow a conviction to stand based on this evidence alone.  The court stated,  "The integrity of the criminal justice system is ill-served by allowing a conviction based on evidence of this quality, whether described as false, unproven or unreliable, to stand."  Barry Scheck, president of the National Association of Defense Lawyers, aniticipates that the FBI's technique will be questioned in other courts.  "You can't use it [the chaining technique] for any probative evidentiary purpose. In many of these cases, people have been wrongly convicted."  More... [Mark Godsey]

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