Minority justices warn that the guilty 'will go free on the most technical grounds.'
The 5-to-4 decision invalidates a Massachusetts law that authorized the introduction of neutral, scientific tests without giving the defendant an opportunity to question the testing technician during the trial.
Now, instead of simply admitting such results as evidence, a technician must appear personally in court to satisfy the requirements of the Sixth Amendment's confrontation clause.
The decision continues an important trend at the high court reinvigorating the right to confront one's accusers. The move began with a 2004 decision called Crawford v. Washington.
Justice Antonin Scalia has emerged as the champion of this newly bolstered right. Writing for the majority on Thursday, he echoed the 2004 decision, saying that the confrontation right is designed to guarantee that evidence is tested in the "crucible of cross-examination."
"Dispensing with confrontation because testimony is obviously reliable is akin to dispensing with jury trial because a defendant is obviously guilty," he wrote.
In an impassioned dissent, Justice Anthony Kennedy accused the majority of casting away 90 years of settled precedent embraced by 35 states and six federal courts of appeals.
"It is remarkable that the court so confidently disregards a century of jurisprudence," Justice Kennedy wrote. "We learn now that we have misinterpreted the confrontation clause ... for the first 218 years of its existence."