Are Polygraphs Admissible in Court in Texas?
Polygraphs are not admissible in court in Texas, like most states because they are considered fundamentally unreliable.
Polygraphs rely on physiological responses to detect whether someone is lying or telling the truth, such as changes in heart rate, blood pressure and breathing.
Lie Detectors
Law enforcement officers employ lie detector tests, also known as polygraphs, to probe those suspected of crimes. A machine measures a person’s heart rate, blood pressure, skin conductance and respiration rate in an effort to determine whether they told the truth or lied.
Polygraphs may appear to be highly accurate, but they are not always accurate. They have a tendency for false positives – which means they could report you as lying even when telling the truth. That’s why it’s best not to take a lie detector test without consulting with an experienced Houston criminal defense attorney before doing so.
Scientists generally do not endorse lie detectors as a reliable method for determining whether someone is telling the truth. Nonetheless, some judges have accepted results of lie detector tests as evidence in certain instances.
For a lie detector to be admissible as evidence in court, it must have undergone testing and been shown to have a high error rate, as well as be widely accepted within the scientific community. Moreover, the theory behind it must have undergone peer review and publication – standards for expert testimony admissibility in court.
Therefore, juries could take into account the results of a lie detector when deciding whether or not to convict someone on a criminal charge in Texas.
Though scientists do not believe lie detectors to be reliable, that shouldn’t stop you from taking one if police ask. Just make sure to consult with a Houston criminal defense attorney prior to agreeing to take the test and be prepared to present all your options. Doing so could help avoid legal issues down the line.
Prescription Medications
A prescription is a written order from a doctor or other qualified medical professional to a pharmacist. These orders typically contain medications like painkillers or other prescription drugs to treat an existing condition; in certain states physicians can also write prescriptions for non-controlled substances.
The Texas Prescription Monitoring Program (PMP) collects and tracks outpatient prescription data for controlled substances dispensed by pharmacies in Texas. This tool can help control prescription drug abuse, diversion and overdose by helping physicians identify patients at risk for overdose or misuse of these medications.
In Texas, prescriptions for drugs are governed by state law and cannot be arrested or charged with a crime simply because someone has a valid prescription. Furthermore, the prosecutor must prove that the individual was intoxicated due to taking their prescribed medicines; not just alcohol alone.
Many people mistakenly believe they cannot be arrested for a drug-related crime because their medicine is legitimate. This misconception should be dispelled, as police officers lack the education and professional medical training to make such determinations.
If you are uncertain whether taking your prescribed medication will affect a polygraph test, consulting an experienced lawyer is recommended. They can explain the legal ramifications of this situation. You may be able to defend yourself against accusations if the polygraph proves unreliable and no alcohol was present during testing.
Polygraphs typically include a dozen questions. Three or four should be pertinent to the topic being investigated, while the remaining two will guide your reactions.
Physiological Responses
Polygraph tests measure and record a person’s heart rate, blood pressure, breathing patterns, and galvanic skin response while they answer questions. Once the test is over, an examiner interprets the data to determine whether the subject has lied.
One type of polygraph instrument is the cardiospymograph, which uses two pneumographs (rubber tubes filled with air). When someone breathes or takes a breath, the air inside these tubes is displaced, causing sensitive needles on the polygraph instrument to move. In digital polygraphs, software interprets this movement and displays it on a computer screen.
Another type of polygraph instrument is a sphygomograph, which utilizes a circular blood pressure cuff worn on one arm. When connected to the polygraph instrument, air is pumped into it which causes constriction in the brachial artery and alters pressure within the tube; this causes needles on the polygraph instrument to move.
The cuff can also be attached to an artificial limb, making it the most popular type of polygraph used in court to detect deception.
There are a variety of factors that can impact the reliability of a polygraph test. Some of these include:
Does lying cause identifiable changes in physiological processes that the polygraph measures? And does the type of lie (rehearsed, spontaneous) influence these changes?
The complex interrelationship between a person’s physiological reactions to questions and the answers they give can be tricky to discern. Thus, lie detector tests were developed in order to monitor these psychophysiological responses in order to make inferences about deception.
False Positives
False positive results during a polygraph test can occur for various reasons. Conditions like anxiety, taking prescription or illegal drugs, and pregnancy all have the potential to make you appear deceptive when in reality you may be telling the truth.
Polygraphs are devices that measure physiological responses in three key areas: heart rate, blood pressure and skin conductivity. Other things may also be monitored during a polygraph, but these three main metrics typically form the focus.
One of the most common physiological changes experienced during a polygraph examination is an increase in blood pressure. This can occur if you’re feeling stressed or guilty, so it’s essential that the examiner know about any medical problems you may have prior to beginning the test.
Prior to beginning a polygraph test, an examiner will go over the procedure with you in detail. This is known as the pretest phase and it’s intended to ensure that both mentally and physically you are prepared.
Before the exam begins, it’s essential to inform the examiner of any health conditions you may have such as hypertension or anxiety disorder. Doing this allows them to adjust their questions accordingly and avoid a false positive result occurring. Furthermore, disclose any medication taken prior to taking the test for extra security.
False Negatives
Polygraph tests measure physiological responses to certain questions, such as heart rate/blood pressure, respiration and skin conductivity (the amount of electricity generated by one’s fingertips). If these physiologic responses are altered through lying or deception, the examiner is likely to believe that someone is not telling the truth.
These physiological changes can be brought on by stress or an underlying medical condition; for example, many people deal with high blood pressure and hypertension.
Due to a health condition that affects your blood pressure, it may be difficult for you to remain calm during the test and answer all questions honestly. This could result in a false positive result.
Other physiological changes that could potentially impair a polygraph exam include sleep deprivation. This is common among those working night shifts or lacking enough rest, but it’s especially detrimental for those taking an exam about a crime from the previous evening.
If you believe your polygraph results are inaccurate, you have the option to appeal and have them reviewed by an independent expert. This will enable you to decide if the original results were reliable and should be used in court.
In certain states, such as Texas, a polygraph test is admissible in court if both parties consent to its submission as evidence. If you’re uncertain whether your results will be accepted in your specific case, consult an experienced Georgetown criminal defense attorney for guidance and protection against unnecessary legal issues.