Investigation and lie detectors.

Like others have said, polygraph tests are not effective at detecting lies.

The police can not force you to take a polygraph test. It is generally not in your best interest to take this test if you are suspected of a crime. Most employers can not force you to take a polygraph test either.

I’ve never been asked to take a polygraph test but my ex was asked. The first time she worked at a Burger King After a theft the manager said all the workers would have to take a polygraph test. The employees got together and decided amongst themselves that nobody would take the test unless the manager also took the test. When they told him their decision he opted not to have polygraph tests. The second time was when she worked as a custodian at a state university. $300 was taken from a broken change machine and even though nearly anyone could have taken the money they decided to give polygraph tests to the custodians. Instead of all the custodians being asked to take the test the manager decided to only test employees he was suspicious of which turned out to be all the black employees. My ex found out that there actually was a employee union for state workers in Texas and called them. The lawyer for the union said that what the boss was trying to do was illegal and made a few phone calls and it was dropped though one custodian volunteered to take the polygraph test to “prove” his innocence but he failed the test and instead of having a cloud of suspicion hanging over him he got another job.