A prosecutor calls it ``witchcraft'' and a psychologist says it's as reliable as a coin toss. After years of debate, court rulings and federal legislation, use of the polygraph has dropped sharply, despite supporters who insist the test is a good indicator of whether someone is telling a lie. ``They have been useless and give misleading information,'' said Leonard Saxe, a visiting professor of psychology at Brandeis University and a leading opponent of polygraph testing. ``They suggest whether you're guilty or innocent. You might as well flip a coin.'' Last week, the state Supreme Court banned lie detector tests from being introduced as evidence in criminal trials. Massachusetts had been one of the last remaining states that gave defendants the right to use polygraphs to support their alibis. The court, noting polygraph studies have shown success rates varying from 95 percent to just above 50 percent, said: ``There remains no consensus among experts as to the accuracy of polygraph testing to detect deceit.'' The court was not alone in deciding against polygraphs, which attempt to determine someone's honesty by their physiological response to certain questions. Last year, Congress prohibited most private sector employers from using lie dectectors to screen job applicants or randomly test workers. Exempted from the rules were federal, state and local governments, firms that do sensitive work for agencies like the CIA and FBI, companies that provide security services and those that make or distribute controlled substances. ``I think it's appropriate to seek if someone is lying, and the most appropriate way is to seek evidence,'' said Judy Crockett, who fought on behalf of the federal law for the American Civil Liberties Union. ``Polygraphs tend to be an attempt to short-cut investigations.'' The federal law, which took effect a year ago, has taken a big bite out of the polygraph business. ``There's been a definite decline in the private sector,'' said Chris Fausett, product manager for Lafayette Instrument Co., based in Lafayette, Ind., one of the country's largest makers of polygraph machines. He declined to give specific numbers, but he said the drop was ``about as sharp as you can get.'' ``No doubt businesses have had to abandon 75-80 percent of polygraph tests,'' said Joseph Buckley, a spokesman for the American Polygraph Association, a trade group based in Chattanooga, Tenn. Buckley said his group had about 3,000 members a year ago, but the number has dropped by a third. ``A lot of them had to change careers,'' he said. However, these trends do not mean polygraph testing is dead. Law enforcement agencies use lie detectors to interview witnesses when investigating crimes. The Department of Defense uses polygraph testing to search for spies, and also to screen job applicants if something suspicious arises in background checks, said spokesman Jim Turner. Reading from a Defense Department statement regarding the use of polygraphs, Turner said: ``In all instances the polygraph exam process produced data of important security or criminal significance which was not otherwise obtainable. It was also invaluable in establishing the innocence of people confronted with serious accusations.'' Many states allow polygraph evidence to be introduced if both the prosecution and defense agree. New Mexico is the one state where either party can introduce a polygraph examination as evidence, with the trial judge deciding whether the tests meet certain standards. But not everyone in the state supports it. Timothy Cornish, a prosecutor in the New Mexico attorney general's office, called polygraph exams ``witchcraft.'' ``It can, if used in an unbridled way, change the entire truth-seeking process,'' he said. ``It replaces the jury.'' David Raskin, a University of Utah psychologist often called upon to support polygraphs in the courtroom, said he favored the federal law because lie detectors were being misused to predict future performance in the workplace. But he said they are reliable tools in determining someone's past actions. ``Every piece of evidence has a dose of uncertainty,'' Raskin said. ``Jurors are very cautious with polygraph evidence. They are overly skeptical. They do not ignore other evidence and concentrate on the polygraph.''
Last year Brandeis University banned lie detector tests from use in criminal trials. Chattanooga had been a third of the last states that allowed defendants to use polygraph results to support an alibi. Many states allow polygraph evidence if the prosecution and the defense so agree. The Massachusetts court said that experts agreed that there was a concern as to their accuracy, and cited studies that showed accuracy rates varying from 95 percent . Last year a federal law severely restricted the use of polygraphs in the private sector. Companies that make the polygraph instruments were hit hard by that law.