Polygraph Examinations

Reasons why a polygraph examination are offered include the desire by the police to: obtain an admissible confession from a suspect or Defendant, eliminate possible suspects to a crime, attempt to learn more information about a crime, confirm parts of an investigation, obtain leverage against other Defendants by attempting to obtain cooperation from an individual, and to preserve resources by not going forward on questionable or suspect cases.

Polygraph examinations, for purposes of criminal law investigations, are completely voluntary.  Based upon the 5th and 14th Amendments to the United States Constitution a person cannot be compelled to answer questions that may result in criminal liability.

A typical polygraph test starts with a pre-test interview to gain some preliminary information to develop possible test questions and to build a rapport with the person questioned.  The person interviewed is read and usually signs a form containing the Miranda rights to establish that the questions are freely, understandingly, and knowingly made.  Also, the person questioned must waive his or her right to an attorney for the purpose of taking a polygraph in order to take a polygraph.  The presence of anyone at the polygraph besides the person being questioned and the law enforcement officer performing the lie detector test invalidates the test results according to the protocol that is followed.

The person taking the polygraph examination has 4 to 6 sensors attached to him or her.  The sensors typically record the person’s pulse, blood pressure, breathing rate, and perspiration.  The readings from the sensors are recorded by ink on a moving piece of paper or by a computer.

A baseline is established by the person conducting the polygraph to calibrate the equipment to the body chemistry of the person being questioned.  During this process the person taking the polygraph is usually asked to deliberately lie in relation to a question in order for the polygraphist (also known as a polygraph examiner) to see if he or she can detect the lie.

When the actual test begins, usually 4 or 5 questions relevant to the issue at hand are asked.   Sometimes control questions are mixed into the questioning to measure changes between control questions and relevant questions so that a change in responses can be read and interpreted by the polygraphist.  The polygraph examiner looks at changes in the readings to determine if a person is lying.  The polygraph examiner’s subjective opinion of the readings is one of the reasons why a lie detector test is not fool proof.

The polygraph concludes with a post test interview.  The person conducting the polygraph will often try to elicit a confession to a particular crime if the polygraphist feels that the person being questioned lied or if the test was inconclusive.  Many previously defensible criminal cases have been undermined based upon statements made at a polygraph examination.  It is important to make no admissions to any criminal activity during a polygraph (unless admitting to a lessor crime is part of a strategy developed in advance of the polygraph with an experienced criminal defense lawyer)  A person who is told that they did not pass a polygraph should not answer any more questions or volunteer any statements.   A person who did not pass a polygraph should ask for his or her attorney to be present during any further questioning and leave when able to do so.  A individual who committed a crime should not take a polygraph with the hope that somehow he or she might pass.

An experienced criminal defense lawyer, such as the lawyers at Hilf & Hilf, PLC, can consult with you to explain the potential advantages and disadvantages of taking a polygraph examination as it relates to your particular situation and help you determine whether taking a polygraph is  in your best interest.  An experienced criminal defense lawyer can help prepare you as to potential questions that could be asked.

Before taking a polygraph it is important to remember that the person performing the polygraph is a law enforcement officer working with the Prosecution.  A polygraphist has extensive training, especially in the area of gaining confessions.  Even through this person may act friendly, he or she is not your friend.  The answers you provide, if you choose to participate in a polygraph test, should not go beyond what is asked of you.  You should always consult with an experienced criminal defense lawyer before agreeing to take, or taking, a polygraph and follow the advice that you are given.

In some cases Hilf & Hilf, PLC arranges for a private polygraph examination to occur for our clients.  We can employ a polygraphist to conduct an examination privately to see how well the client is likely to fare if he or she takes a polygraph examination through law enforcement.  If the client fails the private polygraph, the results remain confidential.  If the client passes the polygraph, the results are shared with law enforcement and the Prosecution with the client’s consent.  In many cases, however, the Prosecution is only satisfied with the polygraph test result if the test is performed by a law enforcement officer that is regularly used by the Prosecution.

In most cases polygraph examinations are not offered based upon the nature of the charge, the proofs involved, and the cost and availability of polygraphists.  Many polygraphists feel that a person’s intent is hard to determine through a lie detector test.  In criminal sexual conduct cases a Defendant’s subjective belief that he or she had a consensual relationship with the alleged victim is often not accepted, even when the Prosecution is satisfied with the polygraph test result.  The way a person or Defendant views the world doesn’t always correspond to how law enforcement views his or her conduct.  Polygraphs are more trusted by law enforcement when the issue is not intent, such as alibi, lack of presence at a crime scene, not taking a particular object, etc.

The passing of a private polygraph may convince the Prosecution to take a closer look at their case.  Taking a closer look at their case might (but does not always) entail offering a polygraph examination through their polygraph examiner, dismissal of the case, a plea bargain, or to reexamine the credibility of their own case.

Passing a lie detector test might lead to a dismissal of a charge or charges, a plea bargain, a sentencing agreement, or it might cause the Prosecution to reexamine their case.  In some circumstances it may lead the Prosecution to seek the cooperation of a Defendant in pursuing a criminal case against other individuals.  In some circumstances, it may lead law enforcement to start an investigation against the person who accused the Defendant in the first place.

For private polygraphs, there is a financial cost involved to hire the polygraphist and an experienced criminal defense lawyer.  Also, if the person fails a private polygraph, family members and friends may not be as supportive as they were in the past if they learn of the result.  However, the result would not be shared by the experienced criminal defense attorney and private polygraphist based upon confidentiality (if done in conjunction with legal representation).

For polygraphs through law enforcement, participating in a polygraph can lead to the introduction of a confession or a statement against interest at a hearing or trial.  If the person fails the polygraph, the Prosecution may be less likely to offer a plea bargain (or may offer a less favorable plea bargain) because any doubt that may have existed was reduced or eliminated in the mind of the Prosecution based upon the failed test result.  The Prosecution may become more determined to gain a conviction based upon the polygraph result, and may act more zealously at trial.  The responses given by the Defendant at this kind of polygraph may also limit or eliminate potential defenses at trial.

A person who actually committed a crime for which he or she is accused should not take a polygraph examination.  Methods to attempt to  cheat or circumvent a polygraph, such as applying anti perspirant all over a person’s body, taking drugs to reduce anxiety or blood pressure, trying to control breathing, etc., are largely detectible by a trained polygraph examiner.  The Prosecution may become more zealous and/or harder to negotiate with if it feels the person is trying to defraud the integrity of the process.