Current Events > So why do police conduct polygraph tests if they're inadmissible in court?

(+) Yeah! (+)

No one has ever really been able to answer that question

To see what people say. To have them on record for given them their account. To do nothing but hurt you at court. To try to break you there.

to pressure the person so they're more likely to elicit a confession

I'm assuming it's to make suspects feel like they're backed into a corner and forced to confess, without actually using contentious interrogation techniques that would yield a coerced confession.

Well, probably because a lot of people think lie detectors actually detect lies.

While they may not be admissible in court, they can give the detectives a direction to go with their investigation. It can help them decide if they are on the right path where they can find rhe sort of evidence they need.

It's also just used as a pressure tool. "You failed the polygraph! We know you did it!! Just tell us how it happened." And some people will fall for that sort of pressure.

Because controlled studies have found that they're slightly better than chance in exposing a lie. But 'slightly better' isn't good enough to be used in court; in a string of good luck, you or I could guess slightly better than chance. Its just a prompt for further enquiry. They're usually just yes/no questions, which makes it easier to trap people in lies, or at least questions that they can't answer in a satisfactory way.

Wobbly line machine go brr

Hmm interesting discussion here; but I guess if anyone is smart they'll just tell the police "well you know these are inadmissible in court right?"

Polygraphs get people to talk. Remember the police's job is to put you in jail. Anything you say can and will be used against you but it cannot be used to help you. It doesn't matter if you give exculpatory testimony under a polygraph, but if you say something they can use to incriminate you they will and they won't bother even attempting to admit the polygraph results as evidence.

lifespeedrunner posted...

Hmm interesting discussion here; but I guess if anyone is smart they'll just tell the police "well you know these are inadmissible in court right?"

Would it make sense to just intentionally stress yourself out over every question, regardless how routine, so that the line is always freaking out and they can't get any read on anything?

Dat_Cracka_Jax posted...

Would it make sense to just intentionally stress yourself out over every question, regardless how routine, so that the line is always freaking out and they can't get any read on anything?

yes. you could, for example, put a thumbtack in your shoe and literally stab yourself with it to pass the polygraph.

There's a scene in The Wire where they bring in a guy and give him a polygraph test. Said test consists of taping his hand to a copier and copying pieces of paper that say true and false on them to line up with the questions they're asking him.

Your average person is dumb. As. Fuck.

They want you to talk. This video isn't about polygraphs, but does a great job covering why you should never talk to the police:

https://www.youtube.com/watch?v=d-7o9xYp7eE

Robot2600 posted...

yes. you could, for example, put a thumbtack in your shoe and literally stab yourself with it to pass the polygraph.

intentional hyperventilating is easier to hide. do it quickly enough and your cns will go into overdrive.

It's just another tool to trick suspects into a confession. Often times cops will even lie about the results to the suspect. The suspect often feels they have to confess even if they didn't do it because of the public's belief that polygraph tests are infallible.

It's no different than cops lying to a suspect that they found their DNA at a crime scene or that a witness reported seeing them.