The average cost of a lie detector test is US$497 or £399. Hence, it’s certainly not cheap to find out if someone is lying or not. Aside from this prohibitive price, there’s also the challenge of whether you can willingly get a person to submit to the examination.
After all, in a democratic society, it’s hard to compel somebody to be tested, unless of course it is dictated by a legitimate court. And then there’s the added challenge of people who can break the test with impunity. These are often psychologists or if not, hardened spies from intelligence agencies around the world.
With all these considerations, the right attitude towards the examination result is to treat it with a grain of salt. For the fact that results can be breached is an indicator that the procedure is not entirely reliable. Unfortunately, many courts of the world still put their faith in the system.