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Admissability of Polygraph Tests in Court

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What Exactly is a Polygraph Test?

A polygraph, or "lie-detector," is a machine that measures various physical attributes (blood pressure, perspiration, heart rate, etc...) and attempts to correlate them with telling lies. In past times they were often used by police and government agents to interrogate suspected criminals, but as they have been proven to be extremely unreliable indicators of lying, their use has lessened in recent years (usually because of court rules prohibiting their use).  

If I Am Arrested for a Crime, Can I Be Forced to Take a Polygraph?

No!  In no state can anyone be forced by the police or anyone else to take a polygraph examination. However, many people are not aware of this, and police can often apply plenty of psychological pressure on a suspect to the effect that not taking the test is an automatic admission of guilt.

Refusing to take a test may often convince police that you are guilty, at which point you may be harassed and searched until some kind of evidence is found. But even if one agrees to take a polygraph test and passes it, if the police consider you a suspect, they may believe you "beat the test" rather than told the truth, making it somewhat of a lose-lose situation.  

What Are the State Laws Concerning Polygraph Admissibility?

Almost every state fits into one of two categories; those that find them completely inadmissible and those that allow their admission with "the stipulations of both parties" (meaning both you and the prosecutor agree to admit the test results as evidence).  

States like California, Arizona, Nevada, Georgia, and Florida allow the tests if everyone agrees to them, but may put different emphasis on the test's accuracy.  

  • California lawyers, for instance, can present the results to the jury, and allows them to draw whatever inferences from it they wish.  
  • Georgia law, on the other hand, allows defendants who suffer damage because of a false result on a polygraph test (which are somewhat frequent) to sue the polygraph operator for damages and attorneys fees. 
  • According to Florida lawyers, it is the one state that does require some people to submit to polygraph tests (previously convicted sex offenders), but even then those test results cannot be used against them in court, and are for use only within the course of their therapy.  

The states in which polygraphs are inadmissible include New York, Texas, Illinois, Pennsylvania, and the District of Columbia. In these states, even if both parties wish to enter polygraph test results into evidence, it is forbidden (except in very rare scenarios). 

  • Some states, like New York and Texas, forbid their use completely in all employment and law enforcement contexts. 
  • Other states, like Massachusetts, do not allow them to be entered as evidence, but CAN use them as supporting probable cause (to obtain search warrants).

Federal courts have their own rules on when to allow the admission of polygraph evidence (it is usually at the judge's discretion). For a complete list of the state and federal rules regarding polygraphs, you can check here for your state.

Do I Need an Attorney?

If you are suspected of a crime, or have already been arrested, and the police are trying to make you take a polygraph examination, you should speak to a lawyer immediately. The police will try to make it seem like refusing the test (or even asking for an attorney!) will lead to your arrest or prove your guilt, but this is absolutely not the case, so it is essential that you have a lawyer present to defend your rights.  No one can ever be forced to take this very unreliable test, and you should speak to an experienced criminal defense lawyer as soon as you can about whether you should agree to one and what would be in your best interest. 

Photo of page author Ken LaMance

, LegalMatch Law Library Managing Editor and Attorney at Law

Last Modified: 02-28-2018 03:10 AM PST

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