Y dont police use lie detecters to see if some 1 is guilty?

Question

just want to know

Answer 1

Lie detectors are a falible machine, if a person can control thier breathing/pulse rate it can be beat and it can also go the other way and prove someone innocent guilty, there really is no way to tell if someone is guilty or innocent that is why we have the jury system.

Answer 2

Lie detectors can be beaten and they are not reliable enough to be allowed in courts

Answer 3

Lie detectors are not reliable.  There are methods to defeat them and, even if those are not used, they can be inaccurate.

Answer 4

nothing is full proof/fool proof in that a person could be made to look like they are lying just because they are really nervous about taking the lie detector but they could actually be telling the complete truth.  Now that goes the other way as well the liar could be detected as being the truthful on because he has learned to control his heart rate and reactions to appear as though he is telling the truth.  So this is not a guarantee that you will have nabbed the right person.

Answer 5

as far as i know, there are two kinds of tests, one measuring heartbeat, and therefore cant always be accurate, but i heard there is a new one they are going to start using that measured brain activity. basically it can determine if you subconciously recognize certain pictures that you would only have seen had you done the crime. i know that method HAS infact been used in a few statea

Answer 6

Because lie detectors are not reliable. People can appear to lying when they are just really really nervous. They can also appear to be telling the truth while they are lying through their teeth. That's why lie detector results are not admissible in court.

Answer 7

Some detectives will use a version of a lie detector, although it is not the common one you may be thinking of. It's one that is used by the FBI, and they would only be used during interviews.

Answer 8

Because a lie detector can be beat.  

Answer 9

They do.  However, they are not terribly reliable, and in many jurisdictions the results are not admissible at trial.

Answer 10

  Can,t use detectore resultsts in court.