Confronting witnesses

In a watershed 5-4 ruling, the U.S. Supreme Court held Thursday that defendants have the right to cross-examine the experts who prepared the crime lab reports submitted in evidence against them.

Such reports have been the subject of controversy and even scandal in the past decade, much of it arising after DNA evidence revealed at least 240 convicted American prisoners were in fact not guilty.

Often, courts allowed these crime lab reports to be introduced simply as factual matter.

In Thursday's opinion, Justice Antonin Scalia found technicians who prepare such reports act as "witnesses" for the prosecution. And under the Sixth Amendment, the accused has the right "to be confronted with the witnesses against him." Justice Scalia wrote for a 5-4 majority that reversed the conviction of a Massachusetts man found guilty of selling cocaine.

Justice Scalia said states can work out procedures that require defendants to notify prosecutors and lab technicians in advance if they wish to question them in court. "The sky will not fall after today's decision," he said.

He was joined by Justices John Paul Stevens, David Souter, Clarence Thomas and Ruth Bader Ginsburg.

The dissenters, led by Justice Anthony Kennedy, said the ruling "has vast potential to disrupt criminal procedures that already give ample protections against the misuse of scientific evidence."

Justice Kennedy insisted "laboratory analysts who conduct routine scientific tests are not the kind of conventional witnesses" referred to in the Sixth Amendment.

But the dissenters are wrong. Yes, it's possible for a defendant or his attorney to try to bog down proceedings by demanding that prosecutors "prove" the sun was up at noontime. Judges will still be expected to exercise common sense and keep things moving.

But experience has shown that many "scientific findings" are indeed subject to challenge, either because the underlying theories prove imperfect, or because the degree of reliability of a given test may not approach 100 percent as closely as believed.

Jurors have a tendency to accept the court's assurance that scientific evidence should be accepted at face value, where we would never tolerate a judge instructing a jury that they must believe any given human witness.

Putting a human face on documentary evidence may involve a little more time and trouble. But protecting the rights of defendants is paramount -- as 240 former convicts, now walking free, can gladly attest.