Massachussetts courts this week will rule on the admissability of polygraph tests as evidence in criminal cases.

In 1978 the Supreme Judicial Court decided in the case of Commonwealth v. Vitello that polygraphs could be used as evidence for the defense on the condition that the person tested took the stand. Critics have argued that polygraphs are unreliable, and New Mexico is the only other state that admits liedetector tests as evidence.

Massachusetts courts will decide whether to admit polygraph tests in four different cases currently on trial. The defenses of three cases involving sexual assault and one of murder are arguing to admit defendants' liedetector tests as evidence.

But experts from both the legal and psychiatric fields are divided over the accuracy of the polygraph test.

"Lying is one of the most complex things we do," David Leonard Saxe, a Boston University psychology professor, said yesterday. Saxe co-wrote a study for Congress on polygraphy and has testified in six Massachusetts cases in recent months.

"A polygraphy examination doesn't measure whether a person is lying because there is no known physiological reaction unique to lying. It's a nice idea that like Pinocchio's nose, our body would give us away when we lie. People can learn to beat a polygraph," said Saxe.

Dershowitz Skeptical

Professor of Law Alan M. Dershowitz said he is also skeptical about polygraph tests but disagrees with Saxe on their admissability in court. "I don't have great trust in polygraph tests, but I do believe defendants have the right to use them in court," Dershowitz said.

But Massachusetts public defenders claim the polygraph has a 90 percent accuracy rate, according to a recent article in The Boston Globe. In addition, the FBI and CIA regularly use polygraphs.

David C. Raskin, a psychologist at the University of Utah, said he has conducted several studies showing that, when properly administered, polygraph tests are accurate enough to be a helpful piece of evidence in the court system.

But critics of the polygraph complain that beating a lie-detector test is too easy, especially when defense lawyers coach their clients on how to lie without detection.