U.S. Supreme Court Decides Defendants Have Right to Question Forensic Expert Who Conducted Tests Used at Trial


The United States Supreme Court held on June 23, 2011, in Bullcoming v. New Mexico that prosecutors cannot use forensic reports as evidence in a criminal trial without allowing the defendant to question the analyst who conducted the testing and prepared the report. The Court made clear that presenting a substitute forensic witness who did not conduct the testing himself does not satisfy the Sixth Amendment right of criminal defendants to confront witnesses against them.

Donald Bullcoming was charged with drunk driving in 2005 after he was involved in a traffic accident in Farmington, New Mexico. At trial, prosecutors introduced a report of blood tests that showed his blood alcohol was three times the legal limit.

The laboratory analyst who tested Mr. Bullcoming’s blood sample and wrote the report had been placed on unpaid leave for an undisclosed reason. Over defense objection, the prosecution presented testimony from a different analyst who worked at the same lab but did not participate in or observe the testing of Mr. Bullcoming’s blood.

Mr. Bullcoming was convicted and he appealed, arguing that admitting the blood test report without giving him a chance to question the analyst who conducted the testing violated his Sixth Amendment right to confront witnesses against him.

The Supreme Court agreed, holding that prosecutors were required to give Mr. Bullcoming a chance to question the analyst who actually tested his blood sample. The Court reasoned that a substitute witness could not testify about what actually happened during testing or whether there were any “lapses or lies” in the analyst’s report. Failing to present the analyst also denied Mr. Bullcoming the opportunity to ask why the analyst was placed on unpaid leave, including whether incompetence, evasiveness, or dishonesty accounted for his suspension.

Bullcoming reaffirms the Court’s 2009 decision in Melendez-Diaz v. Massachusetts, which held that defendants must have a chance to question forensic witnesses whose reports are used at trial because vigorous cross-examination is critical to uncovering bias, fraud, or incompetence.