Legal Aspects of Polygraph Use
In Criminal Investigations
A polygraph examination, also known as lie detection, is a diagnostic test given to someone whose honesty in a statement is in question.
It is carried out by posing a series of questions to the subject while changes in the subject’s body is being monitored using a polygraph device.
Polygraph tests are useful for identifying suspects who might attempt to manipulate the judicial system as well as for bringing justice to many innocent people who have been wrongly convicted.
Polygraph tests provide governmental agencies and legal systems with a practical and simple method of extracting the truth from test subjects. These tests are used by investigative teams throughout the world. While it may not always be effective, using this method along with other investigative processes helps investigative teams ascertain the truth.
Admissibility of the Polygraph Examination/Result
Is polygraph result/examination admissible as evidence in court? The answer is rather complicated.
The answer could be “YES” if allowed by the judge. However, if the test was administered by an unqualified and inexperienced examiner, the results are unlikely to be used by the judges.
Today, there is a lot of activity in the court system regarding the use of polygraphs and the laws are rapidly changing.
Under the following conditions, polygraph and expert testimony relating to it may be admissible with a stipulation to support other evidence of a defendant’s involvement in a crime or to support or charge his testimony:
- That the admissibility of the polygraph test is a matter for the trial judge to decide. The trial judge may reject such evidence if he is not convinced that the examiner is competent or that the result was not obtained under proper conditions;
- That both parties’ counsel and the subject sign a written condition for the subject’s admission to the examination and subsequent admission to further polygraph tests and examiner’s opinion on behalf of either the defendant or the state;
- If the examiner’s opinion is offered as evidence, the opposing party is entitled to cross-examine the examiner on the following topics:
- The qualifications and training of the examiner;
- The stipulation under which the test was administered;
- The restrictions and possibilities for the errors of the technique;
- At the good judgment of the trial judge, any other matter deemed important to the inquiry.