How come in murder cases and missing cases they do not just give the suspect?

LIE DETECTOR TEST! I mean they do give some of them test when it comes around to it but why not give them lie detector test immediately! Don't you think that will make it easier on the jury?How come in murder cases and missing cases they do not just give the suspect?
yea i thought about that and i realized that they're not 100% accurate...if like the suspect (lets just say that he did do it) managed to ';convince'; himself that he aactually didn't..then it wouldn't show up on the test that hes lyingHow come in murder cases and missing cases they do not just give the suspect?
Polygraphs are not admissible in court, because they do not prove anything except how nervous you were. If you have shaky nerves, when they get to the question about the crime you didn't commit, and you get so nervous about failing the test that you actually do fail. On the other hand, some people are compulsive liars to the point where they speak lies like nothing, or the actually start believing the lies. Some people can also train themselves to pass the test.





The reason they sometimes do lie detector tests is that when the pressure is on, the guilty person will break and confess to the crime. That confession is admissible in court.
Because ';lie detector tests'; are worthless.





They are voodoo science of no probative value whatsoever, which is why they are totally barred from use in any trial. Even the fact that someone took, or didn't take, a test cannot be mentioned in court.





Lie detectors have one use, and one use only, in law enforcement - as a 'scare tactic' to pressure poorly educated, or unrepresented, defendants into confessing.





Richard
Lie detector tests are known to be highly innacurate and rarely used. Few USA states use them and in the UK they are not regarded as an acknowledged method of evidence. Lie detectors can be easily misinterpreted and answers are easy to skew... wording a question badly or changes in the room at the time of asking. Having researched it for uni they are not the answer and never will be.


so i have to say i disagree.
A lie detector is not admissible in court. Whether you pass or fail it can't be introduced as evidence--you can even refuse to take one.
1. ';Lie detector tests'; aka polygraphs are not reliable


2. it would be a violation of the suspect's constitutional rights


3. it is inadmissible in a trial
You can not be compelled to give evidence against yourself.
because they are not 100% accurate. to arrest someone for a crime and convict them you need evidence, not just suspicion.
Yes, but sometimes lie detection software is not always accurate.
Lie detectors are not reliable. They can give both false positives and false negatives.