The United States Supreme Court held in June that a state prosecutor may not introduce a lab sheet into evidence against a defendant unless the person who prepared the lab sheet also testifies at trial so that the defense counsel may cross-examine him. This is required, the Court held, by the defendant's Sixth Amendment right "to be confronted with the witnesses against him." Melendez-Diaz v. Massachusetts.

Many states had dispensed with this basic requirement by allowing forensic experts to submit affidavits about their findings for a criminal prosecution rather than appear in court to answer questions. When a defendant is charged based on a laboratory finding, such as a breathalyzer test in a drunk driving case, the expert who performed the incriminating test is often not even provided as a witness in a trial. The jury is expected to take the word of the forensic expert who did the test without ever hearing his testimony, or benefiting from cross-examination of that testimony by the defense.

In the District of Columbia and Maryland, defendants already have this Sixth Amendment right of confrontation, and no change is required to obtain or uphold convictions. But Virginia does not, and within a few weeks of the Supreme Court decision at least five prosecutions for drunk driving were dismissed in Fairfax County on this basis.

Virginia Governor Timothy Kaine responded by calling for a special session of the Virginia legislature to conform Virginia law to the Supreme Court ruling. "If we don't solve it in a special session, it really creates a potential problem of people who are charged with very serious crimes being able to escape conviction on technicalities," Kaine explained.

Critics of the Supreme Court ruling cite additional costs that it imposes on already struggling state law enforcement agencies. In Virginia, for example, there are only 160 state employees in its Department of Forensic Science, and they are responsible for handling about 60,000 cases. There is already a backlog in the processing of evidence even without this new requirement. http://www.washingtonpost.com/wp-dyn/content/article/2009/07/22/AR2009072203533.html

But Justice Antonin Scalia has long championed the "Confrontation Clause" in the Sixth Amendment, regardless of whether it is costly or not. This right is fundamental in protecting against unreliable or false accusations by someone who never appears in court.

There have been numerous reports of fraudulent forensic reports used to convict innocent defendants, sometimes resulting in shockingly long prison sentences. If the person preparing the report knows he will never have to answer questions about it by defendant's counsel, he may have less motivation to be completely accurate.

The Sixth Amendment right of confrontation is not a matter of convenience, but is a fundamental constitutional right, the Court held.