The US Supreme Court on Monday denied certiorari in a case on the Sixth Amendment’s confrontation clause, prompting a dissent from Justices Neil Gorsuch and Sonia Sotomayor.

Under the Sixth Amendment’s Confrontation Clause, “in all criminal prosecutions, the accused shall enjoy the right … to be confronted with the witnesses against him.” The two justices said that cross-examination may be “the greatest legal engine ever invented” for the accused to exercise such right.

Vanessa Stuart’s petition asked the court to apply the decision in Bullcoming v. New Mexico, in which the court held that the prosecution may not introduce a forensic report without offering a live witness competent to testify to the truth of the report’s statements. She complained that the state of Alabama called a different analyst instead of the analyst who performed the blood-alcohol test conducted hours after Stuart’s arrest to prove that she was driving under the influence.

Gorsuch and Sotomayor would have sided with the defendant-petitioner: “the State effectively denied Ms. Stuart the chance to confront the witness who supplied a foundational piece of evidence in her conviction. The engine of cross-examination was left unengaged, and the Sixth Amendment was violated.”

With regard to the state’s argument that the report was not testimonial, Gorsuch said that “a forensic report qualifies as testimonial when it is prepared for the primary purpose of accusing a targeted individual who is in custody, and Ms. Stuart was clearly in custody when the government conducted its forensic test and that the report’s primary purpose is securing her conviction.”

“I believe we owe lower courts struggling to abide our holdings more clarity than we have afforded them in this area. The errors here may be manifest, but they are understandable and they affect courts across the country in cases that regularly recur. I would grant review,” Gorsuch wrote.