Our criminal defense lawyers represent individuals charged with crimes and offenses in Pennsylvania and New Jersey. We frequently receive questions about polygraphs (lie detector tests) and their admissibility in Court. It is important to understand that polygraphs are inadmissible (excluded) from evidence. They are strictly prohibited in Pennsylvania criminal courts but New Jersey does permit them in certain circumstances if there is not a stipulation between counsel as to their admissibility.
This means that in New Jersey a person can take a test, fail it, but if their criminal defense attorney hasn’t stipulated to its admissibility, it is not admissible. In New Jersey, Courts have reversed convictions reasoning that evidence is inadmissible if an un-counseled defendant, without speaking to an attorney, signed a stipulation agreeing that polygraph results would be admissible at trial. The Court found that this violated the Defendant’s 6th Amendment right to counsel.
Where is a polygraph admissible and how does it come into evidence in a courtroom?
Across the country, twenty eight (28) states (including Pennsylvania) prohibit the admission of a polygraph test as evidence while eighteen (18) (including New Jersey) limit the admissibility to only those cases where both parties stipulate (agree) to its use. This stipulation, however, would hardly ever occur because evidence that a person passed or failed a test would substantially damage or hinder either the prosecution or defense argument. The stipulation must be entered into with full knowledge of the right to refuse and the consequences involved in taking it. Finally, he examiner must obviously be qualified and the test be administered in accordance with established polygraph techniques.
What is the science behind a polygraph?
It is important to understand that a polygraph is not actually a lie detector test but evaluates a person’s physical responses to questions. The machine makes its determination based on these physical presentations and not anything within a person’s mind. The machine has no ability to actually determine truth and there are multiple ways of obtaining false/positive results. With that said, a polygraph is never admissible, and we do not advise clients to take them under any circumstances. Criminal charges are extremely stressful and questions relating to them can stimulate various emotions and physical responses.
While the results of the test are considered inadmissible with some exception, it’s important to keep in mind that many law enforcement agencies, along with local district attorney offices, and even US attorney’s offices utilize this technology. While courts have taken issue with its reliability, the instrument itself tests 3 systems within the human body through convoluted rubber tubes which are placed over the examinees chest and abdominal area to record respiratory activity, small metal plates attached to the fingers which record sweat gland activity, and a blood pressure cuff to record cardiovascular activity. While a polygraph is sometimes referred to as a lie detector, it does not tell if a person is lying, but only that there was a physical response to a question which could indicate truthfulness.
False Positives vs. False Negative Errors
Courts consider polygraphs unreliable and errors are referred to as either false positives or false negatives. A false positive occurs when a truthful examinee is reported as being deceptive and a false negative occurs when a deceptive examinee is reported as truthful. There is no conclusive data on which occurs more often and examiners use a variety of techniques and procedures to limit these errors including the following:
- An assessment of the examinees emotional state
- Medical information about the examinees physical condition
- Specialized tests to identify overly responsive examinee
- Control questions to evaluate the examinee response
- Factual analysis of the case information
New Jersey & Polygraph Admissibility
New Jersey is one of those states where parties (prosecution and criminal defense lawyer ) can agree to the admissibility of the polygraph as courts in the Garden State have ruled that a polygraph test have sufficient probative value and are therefore admissible where both parties agree. If parties stipulate, it must be clear, unequivocal and complete.
Who has the burden of proof if you are charged with a crime in Pennsylvania or New Jersey? What is the burden of proof in a criminal case?
Keep in mind that the burden of proof is always on the State or the Commonwealth to prove your guilt beyond a reasonable doubt. This is an extreme high burden. It is a much higher burden then the burden of proof at a preliminary hearing or an indictment (New Jersey). At these pre-trial proceedings there is a preponderance burden of proof (prima facie). There are a variety of reasons why a matter is held for trial, or a person is indicted, but an indictment is not a conviction. It is similar to a Court holding a matter for trial in Pennsylvania.
This is the reason why you retain a criminal defense lawyer as soon as possible as an indictment and/or preliminary hearing is an important part of the process prior to trial.
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