Part 1 of 1 – 95.0 Points

Question 1 of 3 31.0 Points
Compare and contrast one research study or article regarding a voice stress examination to one research study or article regarding a polygraph examination [you may select any criminal, intelligence, security or employment investigation].

Law enforcement agencies are given technologies to help them ease the burden of their work. Having the latest technology is great for all law enforcement, however, truth is that not all agencies can afford them due to cuts in budgets and high costs of owning, maintaining, operating and training. Military personnel that have been involved in that of lie detection have considered the possibility that detection of voice stress can be used in conjunction to speech recognition technology to improve capabilities. Statements have been made by the vendors that with voice stress analysis, officers can test up to 6 a day where the polygraph can only do 2. This is what is attractive to law enforcement agencies. The increase in the amount of testing versus that of training and education. There was also an idea of combining the polygraph and the voice stress analysis machine which may give the investigator an edge.(National Institute for Truth Verification) Although the police use polygraph and voice stress analysis machines routinely in questioning a suspect, the United States Supreme Court held that polygraph tests are not admissible in court because they are not sufficiently accurate and reliable.

Researchers say that the voice stress analysis at best scars suspects into confessions or at worst can incriminate the innocent. CVSA are still not admissible in court basically under the same statue that the polygraph is inadmissible. The VSA came into play in the Cold War Military project in the 1970’s. Research shows that is has no better success in detecting lies than the polygraph. In 1999 a civil rights suit was brought against the San Diego County public affairs officer. The VSA was not only used but used as the sole way of extracting false confessions of murder by teenagers. The statement of 98 percent accuracy is based on satisfied customers and not on independent research. So from what I have gathered, the accuracy and reliability is company based and not research based.

The polygraph research is one that the only ones included is that of tests being administered by professional polygraph testers. Some were independent studies others were that of studies by universities. Even though that there is some evidence that polygraph testing is effective, there is found to have a substantial error rate. This is more true for innocent subjects. There is not study to effectively uncover undisclosed information from screened government employees. This is proven to be a problem of interpretation because they cannot measure adequate truth.

I did include a couple of real world examples:

In the case of Trayvon Martin, Zimmerman was given a voice stress analysis exam. He reportedly passes the test. Joe Navarro was asking questions of Zimmerman but does say that specific questions have to be asked. Some facts are still unclear, however, Zimmerman followed Trayvon to the house where he was staying with his father. In Zimmerman’s first recorded statement, he said that he did not know where Trayvon was. He stated he was afraid of Trayvon. He admitted to exiting his vehicle for the name of the street even though he stated Trayvon was circling his vehicle. Zimmerman passes the voice stress analysis, although his actions were inconsistent with those of someone that stated he was in fear of a subject. As I said above the US Supreme Court ruled that a polygraph and voice stress analysis are inadmissible in court, Zimmerman’s results are not going to be allowed to stand. Some of the questions I saw that was asked were not proper question fomats. Even if the proper formatted questions were used in the voice stress analysis, it would not make much difference due to the fact of reliability.

Another case was that of Gary Ridgeway who was a serial killer and quickly became known as the Green River Killer. He was arrested on unrelated charges of prostitution and quickly became the suspect in 1983 of the Green River Killings. Ridgeway was given a polygraph and passed. However, police took saliva and hair from Ridgeway. He was released due to the fact he passed the polygraph and they were unable to keep him. His undoing was that of DNA evidence found under the victims fingernails.

I think that since the polygraph was used as a sole evidence collector in the Ridgeway case, he was released. It wasn’t until better technology was available before he was caught. It goes to show that the polygraph and the voice stress analysis should be used in conjunction with the investigation and evidence collection. Nothing is a substitute for good old fashioned police work.


1] National Institute For Truth Verification,

2) ^ Park, Haeyoun; Alan McLean, Graham Roberts, Archie Tse (April 1, 2012). “The Events Leading to the Shooting of Trayvon Martin”. The New York Times (The New York Times Company). Retrieved April 15, 2012.

3) Masoninblue. Polygraph Test Result in Zimmerman Case Is Unreliable and Useless. Saturday July 7, 2012.

4) Copyright 2001 Newhouse News Service All Rights Reserved Newhouse News Service November 2, 2001 Friday

Comment: Very well articulated. Remember to watch your citations though- NITV is the inventor of the CVSA, so they will be slightly iased.
Question 2 of 3 31.0 Points
Compare and contrast the limitations or strengths in the utilization of the voice stress examination as oppose to the polygraph examination from the above studies or articles you have selected.

As far as the polygraph is concerned, the problem of using it is that there must be evidence to convict. Enough to erase reasonable doubt. So the false positives or negatives. This creates a problem with the evidence that must be collected so that there is an overwhelming pile of evidence to be able to take away one’s freedom. The Constitution states that no one is to be deprived of life liberty and the pursuit of happiness without due process. (Paraphrasing of course) If that is the truth, then the polygraph is not the way to do it. The reliability is sketchy at best. It maybe able to help open up the possibility of more leads or a direction that an investigator can go but to use it as a sole purpose to incarcerate someone is no better than that of the Salem Witch Trials on simple accusations that they could not prove. There is always the difference in variability and accuracy rates across the US. That unfortunately is probably attributed to human error. The other problem that I can see is that of the level of either anxiety or underlying psychological issues. Since the polygraph is pretty much a measurement of blood pressure, heart rate and pulse, then if someone has a psychological fear of being persecuted or punished, I would say that they may be under stress and that the reliability of the test may be faltered. Detection of deception involves results that effect the people for the rest of their lives. The evidence should be weighed carefully to see if there is something that has been missed and validate what the investigator already knows.

The Voice stress analysis is a scientifically invalidated techniques for screening applicants or disciplining employees may subject the investigator to legal and moral implications. The only thing that separates the polygraph from the CVSA is that of the display on the computer screen versus paper. There are no scoring systems or analytical methods for interpreting the results of the CVSA. Although the CVSA is used to detect high stress in the offender’s voice, there is not science to back it up. There have been claims that is it a pseudoscience. The other issue is that there is no government regulation of these devices. Each state or department is left to regulate their own. The CVSA has been highly criticized as biased, unscientific and industry funded.

I think that the researchers might actually be right. There is really no scientific basis to measure either of these devices. I have not found any scientific basis for the findings either. The critics might be right on this one when they say that it is industry funded research and bias. I would say my product was valid if I wanted you to buy it. I am not sure of the actual validity and reliability of either machine. I have to say that if these machines are used alone, it would create a problem with taking away one’s right to a fair trial.


1] National Institute For Truth Verification,

2) ^ Park, Haeyoun; Alan McLean, Graham Roberts, Archie Tse (April 1, 2012). “The Events Leading to the Shooting of Trayvon Martin”. The New York Times (The New York Times Company). Retrieved April 15, 2012.

3) Masoninblue. Polygraph Test Result in Zimmerman Case Is Unreliable and Useless. Saturday July 7, 2012.

4) Copyright 2001 Newhouse News Service All Rights Reserved Newhouse News Service November 2, 2001 Friday

Comment: Well done.
Question 3 of 3 33.0 Points
Compare and contrast the legal issues regarding the evidentiary value of polygraph and voice stress and their acceptance or non-acceptance in court.

Over the Past almost century, lie detection has been excluded from courtrooms in all forms. Lie detection is not a recent development. People have been trying to detect deception and persons telling the truth for many years. As the technology has increased so has the effort to make lie detection more scientific.

The first legal opinion addressing the issue of lie detection evidence came in 1923 in Frye v. United States. The Court of Appeals for the D.C. Circuit set a longstanding precedent for both the general standard of scientific evidence and fortunately one that would govern for around 50 years, and the exclusion of lie detection evidence. On appeal, the court upheld the lower court’s decision to exclude the technology based on the fact is was not generally accepted scientific evidence. This became know as the Frye standard. This was replaced in 1960 by the Federal Rules of Evidence, and then again in 1993 with Daubert v. Merrell Dow Pharmaceuticals. However, Frye remains standard in many jurisdictions (Frye v. United States, 293 F. 1013)

The Supreme Court finally dealt with the issue in 1997 in United States v. Scheffer. From a decision of the United States Court of Appeals for the Armed Forces, the Supreme Court addressed the constitutionality of a longstanding per se ban on the use of polygraph evidence in court-martial proceedings. (Scheffer, 523 U.S. 303, 306–08 (1998))

The Court held that a per se ban on polygraph evidence does not violate a defendant’s right to a proper defense under the Sixth Amendment. Inappropriate application of dicta from Justice Thomas’ opinion in Scheffer has become fodder for courts looking to uphold the exclusion of lie detection in a number of jurisdictions. (Scheffer, 523 U.S. 303, 306–08 (1998)).

Some critics call for the further research into the validity of the polygraph. The case of Scheffer does not address the possibility of systemic bias. There has been a suggestion that no other form of evidence has come under such scrutiny and excluded on legally unjustifiable grounds. Critics fail to explore why the polygraph is held to a higher standard. However, the polygraph is accepted in some jurisdictions. Currently only 29 states bar the polygraph evidence under any circumstances. The problem in many jurisdictions is the problem of validity and reliability since there is not real scientific standard to measure the polygraph by.

For example, the Eighth Circuit Court of Appeals excluded polygraph in United States v. Alexander based on “careful review of the numerous materials presently available discussing polygraph.”Specifically, the court cited lack of general acceptance as a justification for the exclusion. Chief Judge Gibson wrote, “ased upon the conclusion that the polygraph does not presently command general scientific acceptance . . . the District Court did not err in refusing to admit the unstipulated polygraph evidence.” (United States v. Alexander, 526 F.2d 161, 164 (8th Cir. 1975). )

In the readings that I have done, I have found that each jurisdiction has their own say on the admissibility of the polygraph. I do see that some of the polygraphs are still held to the Frye and Daubert standards. The scientific community has issues with the polygraph due to the fact that there is no way to scientifically measure and validate the testing outside of the biased interested parties that are trying to sell products.


1) Paul V. Trovillo, A History of Lie Detection, 29 J. CRIM. L. & CRIMINOLOGY 848, 849 (1939).

2) Daubert v. Merrell Dow Pharm. Inc., 509 U.S. 579, 586–87 (1993); Stolfi, supra note 35, at 862.


4) Scheffer, 523 U.S. 303, 306–08 (1998)

5) United States v. Alexander, 526 F.2d 161, 164 (8th Cir. 1975).

6) FRYE v.UNITED STATES. 293 F. 1013 ( D.C.. Cir 1923).

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