Many people, especially those accused of a criminal offense, often wonder how polygraph tests—commonly known as lie detector tests—actually work. Are the tests reliable? What methods are used to determine whether someone is being truthful or attempting to “beat” the test?
While polygraph results are generally inadmissible as evidence in South Carolina courts, the process itself can be a source of stress and uncertainty. If you’ve been charged with a crime or are under investigation as a suspect, law enforcement officers may ask you to take a polygraph test. In some cases, you might even consider volunteering for one to prove your innocence.
However, it’s important to understand that in South Carolina, you cannot be compelled to take a lie detector test.
We will address common questions asked of our criminal defense lawyers at Johnson, Johnson, Whittle, Lancer and Staggs (JJWLS) on whether it’s possible to beat a polygraph test and explain why agreeing to take one—even if you are confident in your innocence—may not be in your best interest.
How Polygraph Tests Work
A polygraph test, commonly known as a lie detector test, is a tool designed to measure physiological responses to determine whether someone is being truthful. It records metrics such as heart rate, blood pressure, respiration, and skin conductivity to detect changes associated with stress or deception.
During a polygraph test, a trained examiner attaches sensors to the suspect, typically on the fingertips and chest, to monitor physiological responses. Before starting, the examiner explains how the test works, including the structure and wording of the questions.
The test begins with control questions—simple ones about basic personal details like your name, age, or where you live. These questions establish a baseline for comparison.
As the test progresses, the examiner introduces questions related to the alleged crime, observing how your physiological responses—such as blood pressure, respiration, heart rate, and perspiration—change when answering these compared to the control questions. Additionally, your facial expressions, tone of voice, and physical movements may be noted.
Despite the detailed process, according to the American Psychological Association (APA) polygraph results are not always reliable. Factors like anxiety, medical conditions, or natural variations in breathing and heart rate can impact the results. Due to these inconsistencies, polygraph results are generally inadmissible in court.
Physiological Measurements
A polygraph measures changes in physiological signals, including:
- Heart Rate and Blood Pressure: Increases may indicate stress or anxiety.
- Respiration: Alterations in breathing patterns can be telling.
- Skin Conductivity: Sweating increases electrical conductivity, which is monitored during the test.
The Role of Baseline Questions
Examiners establish a baseline by asking control questions that are unrelated to the investigation (e.g., “Is your name John?”). These responses are compared to answers for relevant questions to detect discrepancies.
Interpreting Results
Polygraph examiners analyze the physiological responses to determine whether deception is likely. However, the interpretation process is subjective and can vary between examiners.
Can Polygraph Tests Be Beaten?
Many people feel anxious about taking a polygraph test and often turn to the internet to learn about the process or ways to “beat” the test. Unfortunately, some of the popularly suggested techniques not only fail but can also backfire, making you appear deceptive to the examiner.
Techniques to Manipulate Results
People have tried various methods to manipulate polygraph results, such as:
- Controlling Breathing: Attempting to maintain even breathing.
- Inducing Stress: Creating discomfort during baseline questions to skew results.
- Physical Countermeasures: Subtle physical actions to disrupt readings.
While these techniques are widely discussed, they are unlikely to succeed. Trained examiners are adept at identifying such tactics, and consistent manipulation is difficult to sustain.
Challenges in Beating a Polygraph
Maintaining consistent physiological responses requires extreme focus and control. Even the most seasoned individuals struggle to deceive the test without detection.
If you are the subject of a police investigation, follow this critical advice:
- Consult a Lawyer First: Never agree to take a polygraph test before speaking with an attorney.
- Consider a Private Polygraph: If your lawyer deems it beneficial, take a private polygraph first to assess your suitability for the test.
- Follow Your Lawyer’s Recommendations: Only take the police-administered polygraph if your lawyer advises it.
This advice applies even if you believe you’ve been unfairly accused or are innocent. While polygraph tests can be accurate, false positives do occur. Discovering you’re not a good candidate for the test at the police station—when it’s too late—can have serious consequences. Always prioritize legal counsel before making any decisions about a polygraph test.
Limitations of Polygraph Accuracy
Polygraph tests are not infallible. Factors like nervousness, medical conditions, or examiner bias can result in false positives (indicating deception when there is none) or false negatives (failing to detect actual deception).
The Reliability of Polygraph Tests
Studies have raised questions about the reliability of polygraph results. While proponents claim high accuracy rates, skeptics argue that the results are influenced by subjective interpretation and human factors.
Admissibility in Court
In South Carolina and many other jurisdictions, polygraph results are often inadmissible in court due to their questionable reliability. Courts recognize the potential for error and the test’s inability to provide definitive proof of guilt or innocence.
Human Factors
Emotional states such as anxiety or fear—even in innocent individuals—can skew polygraph results. Similarly, medical conditions affecting heart rate or respiration may lead to inaccurate readings.
Legal Implications of Taking a Polygraph Test
In most cases, taking a polygraph test is voluntary. Exceptions may arise in certain employment contexts or during criminal investigations, but you generally have the right to decline.
How Results Are Used
Polygraphs are investigative tools rather than definitive evidence. While they can inform an investigation, their results are not conclusive proof of guilt or innocence.
Why Legal Advice Is Essential
Consulting an attorney before agreeing to a polygraph test is crucial. An experienced lawyer can advise you on whether taking the test is in your best interest and help you prepare if you choose to proceed.
What to Do If You’re Asked to Take a Polygraph
While polygraph tests are not admissible in South Carolina Courts, police offices will still try convincing suspects to submit to a lie detector test. If you are charged with a crime, law enforcement officers may exert pressure on you to take the test and even suggest you’re guilty for not agreeing to take it. However, it’s not a good idea to submit to the test, even if you know you’re innocent.
- Know Your Rights: Understand that in most situations, you can decline to take a polygraph test. Familiarize yourself with your legal rights before making a decision.
- Speak with an Attorney: Always consult a criminal defense attorney if asked to take a polygraph. They can evaluate your situation and provide guidance on the best course of action.
- Prepare for the Test: If you agree to take a polygraph, approach it with a clear mind. Follow your attorney’s advice, answer questions truthfully, and remain as calm as possible.
Keep in mind that even if you pass the polygraph test, the charges against you will not necessarily be dismissed. The police could just claim that you’re a good liar. Moreover, the results are not admissible in court.
Talk to a Criminal Defense Lawyer in Aiken, South Carolina
Polygraph tests are often surrounded by controversy regarding their reliability and accuracy. While they can be a useful investigative tool, they are not foolproof and are rarely admissible as evidence in court.
If you are ever asked to take a polygraph test, remember to:
- Understand your rights.
- Seek legal advice from a qualified attorney.
- Carefully consider your options before agreeing to the test.
For expert legal guidance and representation, contact Johnson, Johnson, Whittle, Lancer, & Staggs today by calling (803) 649-5338. We are here to protect your rights and help you navigate the complexities of the legal system.
