Reinforcing the measures already taken by more than 20 state legislatures, a court decision has tightened restrictions on how employers can use polygraph tests to determine the honesty of their employees.

Laws in 22 states and the District of Columbia say that an employee has the right to refuse to take a lie detector test required by his or her employer. In response to these laws, many employers have made signing a waiver of this right a condition for being hired or for continued employment. But in a recent ruling in Philadelphia, the U.S. Court of Appeals for the Third Circuit said requiring employees to sign such a waiver is illegal because it undermines a Pennsylvania state law that forbids employers from mandating any sort of cooperation from employees on lie detector tests. Many experts view polygraph results as inherently unreliable.

In Polsky v. Radio Shack, a U.S. district court judge had originally found that Bonnie Polsky, manager of a Radio Shack outlet in East Norriton, Pa., had waived her rights under the Pennsylvania law when she signed a release form and took a lie detector test following a robbery at the store. Polsky was fired as a result of the test, but she sued Radio Shack, claiming she had been instructed to sign the release and submit to testing or be dismissed. Since she hadn't been coerced physically into signing the form and had been reminded of her right not to sign, the district court said Polsky could not renounce her waiver after her decision.

The appeals court found otherwise. While it was true that Polsky had not been physically forced by her employer to sign the release, she persuaded the court that putting her signature on the form had been a condition for keeping her job -- in violation of the spirit of the Pennsylvania law. Noting that employees are in a "uniquely vulnerable position," the appeals court stated that an arrangement such as a release, because it frees employers from liability under the lie detector laws, is not legal.