Supreme Court Issues Murky Decision on Crime Lab Testimony


A 5-4 ruling from the U.S. Supreme Court on Monday has muddied the debate over whether or not a criminal defendant has a right to cross-examine forensic analysts who provide scientific evidence at their trial. According to the Sixth Amendment’s confrontation clause, a defendant has a right “to be confronted with the witnesses against him.” Based on that principal, the Court decided in

Melendez-Diaz v. Massachusetts

in 2009 that the forensic analyst who performs testing must also testify.


Monday, the Court issued a plurality decision with four separate opinions in

Williams v. Illinois

limiting criminal defendants’ rights under the confrontation clause. In the case, the Court upheld a sexual assault conviction where the prosecution called an expert to testify that the defendant’s DNA matched the profile found on evidence, but the prosecution didn’t introduce the lab results or call the analyst from Cellmark Diagnostics who performed the testing. Because a majority of judges could not agree on a single rationale for upholding the conviction, how it will apply in future cases is unclear.


The New York Times


Justice Kagan began her dissent with a description of another case, one in which a Cellmark analyst took the stand, only to realize after cross-examination that she had made a “mortifying error” in wrongly concluding that DNA from a bloody sweatshirt matched that of the defendant.


The confrontation clause, Justice Kagan wrote, is “a mechanism for catching such errors,” demonstrating “the genius of an 18th-century device as applied to 21st-century evidence.” Justices Scalia, Ruth Bader Ginsburg and Sonia Sotomayor joined the dissent.


“Under our confrontation clause precedents,” Justice Kagan added, “this is an open-and-shut case.” But the decision issued on Monday, she said, had turned a clear rule into a murky one. She urged lower courts to continue to follow the recent rulings on crime lab evidence “until a majority of this court reverses or confines those decisions.”

Unvalidated or improper forensic science

played a role in approximately half

of the 292 DNA exoneration cases.


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and a similar ruling,

Bullcoming v. New Mexico


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