Why don't they have lie dectectors in court rooms?

Question

I just thought of that since they can tell if your lying or not.

Answer 1

Because lie detectors are not accurate. In many cases both parties believe 100 percent that everything went down as they said and both would come up negative especially if one of the parties is a schizophrenic or a sociopath. Also people with heart conditions or disorders like ataxia or Parkinson's disease may trigger a false positive.

Answer 2

not one of the different answerers have have been given it particularly top. i'm an criminal expert, and that i will help you understand that the rationalization why polygraph (lie detector) outcomes at the instant are not allowed in court is partly because of the fact they don't look to be a hundred% precise in each case, yet additionally whilst shown the evidence, a jury may well be in all probability to have confidence that the outcomes have been particularly precise devoid of regard to the reliability of polygraph assessments. this might unfairly prejudice a defendant's case - human beings might say, oh nicely a device stated he's mendacity so he could be! The criminal term of paintings is that polygraph evidence is extra prejudicial than probative. If a defendant is particularly responsible, there'll continually be different evidence as nicely a lie detector to teach his or her guilt. Swearing on a Bible does not bypass to credibility the comparable way - everybody is asked to do it.

Answer 3

While it is true that lie detectors are not used as permissible evidence in court because they are unreliable, the real reason they cannot be used as you described is a legal one: it's unconstitutional. The 5th Amendment provides for protection from self-incrimination, and a lie detector would assume to either validate or incriminate a person's statements without their consent. In addition, it would defeat the purpose of making statements under oath -- there is no such thing as the presumption of innocence if a machine tells the jury that someone is lying.

Answer 4

Lie detectors cannot actually test if you are lying or telling the truth. They would have to be mind readers! What they can do, however, is measure physiological responses, such as heart rate, and their changes as you answer the questions. A sudden increase in heart rate, for example, may indicate that you are being deceitful to the extent that it is common for people to get nervous when lying, and an increase in heart rate is associated with being nervous. That does not, per se, PROVE that you are lying, only that your heart rate has increased.

While they can INDICATE that you MAY be lying, they cannot prove it, and therefore are not nearly a reliable enough source to be admissable within court settings.

Answer 5

Because they are inaccurate. Some people know how to fool them. That means that they can lie but not have it be detected as so. Also, people can fail one even if they are telling the truth if they are nervous or something like that. This creates a reasonable doubt. With that, any defense team could get the polygraph results thrown out because of this reasonable doubt. So why even bother allowing it as evidence.

Answer 6

A polygraph instrument is basically a combination of medical devices that are used to monitor changes occurring in the body. As a person is questioned about a certain event or incident, the examiner looks to see how the person's heart rate, blood pressure, respiratory rate and electro-dermal activity (sweatiness, in this case of the fingers) change in comparison to normal levels. Fluctuations may indicate that person is being deceptive, but exam results are open to interpretation by the examiner. it is not reliable in the least, unless you use it to see if people are nervous.

Answer 7

The same reason that the results of a lie detector test can not be used as proof in a court - they are unreliable. Crooks can beat the test and innocent people can fail them.

Answer 8

because lie detectors are not foolproof and can be tricked....they measure certian biological patterns in the body that if a person trains themself well enough they can trick and fool...and while everyone is convinced they are telling the truth they are in fact lying.

Alternatively people who natually get overly nervous will register lies when they are telling the truth...it is a faulty technology.

Answer 9

Because they can't tell if you're lying or not.

Lie detectors are accurate in telling if the individuals is being truthful.

But, many factors could cause a bad reading.

Answer 10

A lie detector (polygraph) is not foolproof. Trained subjects and certain individuals can beat the machine. Thus, they are not allowed.