Everything You Need To Know About Polygraph Testing



Crimes Investigated With Polygraph Testing


Polygraph screening is generally accepted as a valid format for forensic applications and investigations. Forensic polygraph screening is a useful tool to use in legal cases where the defendant wants to prove their innocence, or where the suspect cannot be proven guilty with witness testaments or hard evidence. The applications of these tests have commonly been used within the justice system as a means to determine the truth or create evidentiary support.


Forensic polygraph testing is a kind of investigative tool that can be used to assist investigators in gathering and collecting corroborative evidence. The results of a polygraph test become incredibly valuable sources of information that are useful when determining a final verdict in a legal case. However, the admissibility of polygraph test results in a Court of Law depends on the case at hand. While there are a few cases where the lower courts have accepted polygraph test results as evidence, there has yet to be a scenario where the high court either accepts or denies the admissibility of these results.


Regardless, lie detector tests are still applicable in a number of forensic cases where there is minimal evidence to determine guilt or innocence. Law enforcement officials, forensic psychologists and criminologists will often make use of polygraph testing. Also known as a ‘lie detector test’, the machine measures one’s physiological responses to a series of yes or no questions about one’s background, behaviours and involvement in suspicious activities. Below is a list of some of the cases in which a lie detector test might come in handy.


  • False accusations
  • Statement verification
  • Sexual harassment accusations
  • Witness statement verification
  • Sexual abuse accusations
  • Rape allegations
  • Domestic violence complaints
  • Criminal negligence accusations
  • Criminal behaviour accusations
  • Child custody cases


Polygraph Machines Measure Physiological Responses to Questions




A polygraph machine collects psychological data from the body using electronic sensors that are attached to the patient’s abdomen and chest. Adhesive electrodes are attached to the fingers to record the activity of the sweat glands, and any other motion, which activates in response to anxiety or fear. Blood pressure is also measured using an arm cuff that records the patient’s cardiovascular activity.


Polygraphists may use conventional instruments, analogue instruments or computerised instruments. The first part of the test is the pre-test briefing where the examiner will explain the proceedings. The second part of the test is when the examiner will ask the patient a number of questions, administer and collect the data sheets with the respective physiological readings. Finally, the examiner will analyse the readings and offer an explanation of their final analysis based on the information collected – if there are any discrepancies thereafter then the examiner will seek out a second opinion, conduct a quality control test, or schedule the test to be taken again.


Although it does not happen often, some polygraph tests do contain false positives or false negatives. As with everything, mistakes happen. However, Polygraph Truths ensures that all of its examiners have undergone rigorous training whereby they learn how to spot errors and correct them. If datasheets are misread or answers have been wrongfully interpreted, then the test can be retaken or reviewed. With the help of senior management, colleagues, supervisors and quality control practitioners, it is unlikely that answers will be misinterpreted or misread.


Conducting Polygraph Tests for Children or Family Conflicts


There is no minimum age requirement for somebody to participate in polygraph testing, and there is similarly no restriction on who can partake in polygraph testing. However, in order for a person to participate in polygraph testing, they must have a good understanding of the English language and they must be able to comprehend abstract concepts while still verbalising their thoughts and responses. For this reason, it is preferable that anyone who participates in polygraph tests is over the age of 12.


Children might participate due to misbehaviour in school, involvement in juvenile criminal activity, or to offer testimony for their experience with domestic abuse or child custody cases, for example. Teenagers often get involved in criminal issues due to rebellious urges or peer pressure, and these issues have to be attended to urgently. If a school attempts to suspend or expel a child over these kinds of allegations, then it is in the family’s best interest to pursue polygraph screening as a means of offering evidence to defend their case.


Similarly, it is common to hear about sensitive issues where family members are involved in domestic abuse. Polygraph screening is often used in cases of family conflicts where parents, children or child protective services are seeking out neutral truths in emotionally-charged situations. In these scenarios, the test offers useful conclusions to any allegations that might be made against someone. Below is a list of examples of family conflicts that might call for accredited polygraph testing.




  • Family Conflicts
  • Accusations of theft or abuse by a babysitter
  • Missing or damaged property caused by family members
  • Accusations against a domestic helper regarding theft or abuse
  • Parental neglect of their children
  • Sexual, physical, emotional or verbal abuse of a child by a parent
  • Sexual abuse of a child by an extended family member
  • Young Adult Conflicts
  • Shoplifting
  • Sibling Physical or Sexual Abuse
  • Skipping school
  • Drug addiction
  • Illicit drug sales
  • Physical assault and aggression
  • Abusing prescription drugs
  • Smoking cigarettes on school property
  • Cyber-bullying
  • Stealing money
  • Sharing pornographic media
  • Damaging or vandalising property
  • The use of marijuana
  • Stealing funds
  • Cheating on examinations or standardised tests
  • Driving under the influence
  • Driving without a license
  • Threatening, blackmailing or extortion
  • Hate speech


Knowing Your Rights: Polygraph Testing Legislation In South Africa




In order for polygraphs to be conducted ethically and legally, the person taking the test must be consenting and should preferably offer agreement either verbally or within a written contract. It is illegal to force a person to undergo polygraph testing, and it is unconstitutional to misuse the results of a polygraph test for exploitative purposes. In South Africa, polygraphs are regularly used for issues surrounding employment law during labour disputes, although there is no specific legislation to regulate the use of polygraph testing in the country.


In the case of labour disputes, it is highly possible that an employer might ask an employee to participate in polygraph testing in order to investigate their misconduct in the workplace. For example, an employer might have reasonable grounds to believe that one of their employees is engaged in serious alcohol abuse, the sale of drugs, fraudulent behaviour, property theft or vandalism. In these cases, it is unlikely that the perpetrator will make an admission of guilt, so the employer might make use of polygraph testing.


The Commission for Conciliation, Mediation and Arbitration (CCMA) accepts polygraph test results as legitimate evidence for investigations that lack eyewitnesses or material proof of the accusation. While the results of the polygraph test may not necessarily be used as valid proof of guilt, it will be used to further support any other evidence or claims of misconduct. In collaboration with other evidence, polygraph tests are a solid foundation to argue for or against a legal case.


Standardised Polygraph Test Procedures




There is also a regulated standard that is enforced amongst polygraphists in order to prevent the unethical application of polygraph testing. For example, the polygraphists at Polygraph Truths are licensed professionals with certified qualifications from accredited institutions. Practising polygraphists have to maintain a certain level of moral behaviour in order to do their jobs effectively, so those undergoing the test can expect that it will be held under the correct conditions.


For example, when it comes to pre-employment screening procedures and polygraph testing, polygraphists are prohibited from inquiring about your religious beliefs and affiliations, your sexual preferences, your political beliefs and affiliations, or your involvement with labour organisations. Polygraphists are also prohibited from sharing the results of your polygraph test with anyone except the predetermined parties involved. This means that your right to privacy will be upheld at all times, and your responses will only be surveyed by authorised personnel.


In order to prevent the results of your polygraph tests from being skewed, there are a few procedures that polygraphists will enforce. Polygraphists will generally check the emotional well-being of the patient beforehand to see whether they are mentally well enough to take the test. They will also check the physical well-being of the patient by asking for medical information that can determine whether the patient has any underlying physical conditions.


The polygraphist would also run a control test to ensure that the machine is working properly. The polygraphist would ask the patient a few basic questions about their personal identity, such as their name, age and country of origin. If the patient answers truthfully and the machine does not pick up any physiological responses that could indicate dishonesty, then the polygraphist can confirm that the conditions are sufficient for the remaining case-related questions.


The polygraphist will also offer their patient a briefing on the procedures of the test, stipulating the kinds of questions being asked and sharing a detailed review of the questions. Once the polygraph test is concluded and the results have been finalised, the answers will undergo quality control reviews by the polygraphist’s supervisors. If the patient is unhappy with their test or claims that they were not in the right mind to answer fairly and honestly, then they can pursue any of the following routes to redeem themselves:


  • Request another test
  • Request that the tests be reviewed again by an independent polygraphist
  • File a complaint with the polygraph company or the Department of Labour


Similarly, If the test was conducted for labour dispute purposes, and the patient felt that it was executed unfairly, then the patient can file a complaint with the CCMA and the Department of Labour. However, it must be noted that while these options are available to patients, the regulated procedures that are upheld within Polygraph Truths will generally prevent this kind of issue from arising. Regardless, it is still incredibly important to be informed.


Find The Truth With Polygraph Screening


polygraph-testing-dictionary-series-philosophy-truth-9764169 (2)-min


Polygraph Truths is a registered service provider with years of experience in the industry. The examiners at Polygraph Truths are certified, licensed and expertly qualified to handle each case with neutrality, sensitivity and professionalism. The results from a polygraph test can be used to justify a verdict, end a family conflict, confirm infidelity, corroborate supporting evidence, screen potential employees and more.


At Polygraph Truths, customers can receive a free consultation to discuss their needs and expectations before they commit to the test. Clients will be guided through the procedures and objectives of services such as pre-employment screening, periodic screening, incident-specific screening, and infidelity screening. Polygraph Truths has conducted over 1000 successful investigations, and the company is accredited by the American Polygraph Association. Call Polygraph Truths today if you’d like to know the truth once and for all.