Are you considering a career in law enforcement? If so, you’re going to have to undergo a pre-employment polygraph. This practice is outlawed in private-sector companies, but it’s legal in public-sector organizations, such as the police forces, intelligence, and the Department of Justice.

The police polygraph is part of the background check the police services do when assessing you as a candidate for a position on the force. Candidates are tested in 15 areas, known as “Job Dimensions for Police Officers.”

Additionally, you’ll be questioned by the polygraph examiner if what you revealed to the background detective checking into you is true. They’ll inquire about traffic history, drug use, undetected criminal involvement, illegal gambling habits, and other pertinent information revealed or discovered during your background investigation. This also includes your military and employment history.


Understanding the Process of Applying to the Police Services

To get a law enforcement job, applicants must undergo a stringent hiring process involving several steps. All candidates looking for a job with the police must undergo a physical and written exam and pass a background investigation before they’re admitted to the force.

The background investigation is thorough, and you need to understand what’s involved with the process and what it looks for during the check. Part of the background check involves the prospective officer taking a polygraph exam.

However, most candidates don’t know what the polygraph constitutes, the questions they have to answer, and the test parameters. Understanding this information helps you better prepare yourself for the polygraph exam.

Preparing for the test isn’t illegal, and your polygraph examiner expects you to learn more about the process before stepping into the exam room. By preparing yourself for the test, you remove anxiety and stress when taking the test, allowing for more accurate results from the polygraph exam.

Everyone is capable of taking and passing the police polygraph exam. There’s no need to be afraid of taking the test; just perceive it as another way to prove yourself to the organization and present yourself as the best candidate for the job.

The Police Polygraph Unit is responsible for administering the lie detector test to officers, victims, suspects, and witnesses involved with police investigations. The PU also conducts lie detector exams on new candidates and personnel seeking reassignment to special task forces.

The Polygraph Unit consists of polygraph examiners who are not part of the force, they’re civilians hired for their past experience in working with local or federal law enforcement, and many of them have time serving in police departments before moving on to a career as a polygraph examiner.


A History of the Police Polygraph – The Early Years

The first use of the lie detector device in police history was in the 1920s. A UCLA medical student, John A. Larson spent his spare time moonlighting with the Berkeley Police Department. His commanding officer introduced him to the work of Dr. William Marston, the first American to develop a lie detector system he called the “Systolic Blood Pressure Test.

Marston’s work revolved around the principle that a suspect blood pressure would increase when they were under the stress of police questioning. Larson found himself captivated by Marston’s work and committed to developing his own lie detector. Larson successfully debuted his device, “The Sphyggy,” in 1921.

His device was further advanced by Leonard Keeler, who refined its workings, increasing its accuracy and ease of use in his design, known as the “Emotograph.” Keeler would redevelop his design several times before his death in 1949 at the age of 45. However, his development partner, “Associated Research,” would further Keeler’s designs, releasing several Keeler polygraph models between the 1930s and 1960s.

Other companies, such as Lafayette Instruments and Stoelting, jumped on the bandwagon, releasing polygraph machines from the 1930s to the 1960s. However, Keeler and Larson earned the title of the “father of the modern polygraph.”

While these devices were successful, Axciton Systems changed the game in the 1990s, releasing the first software-driven polygraph device. This innovation caused a shift in the industry towards computerized systems.


What is the Police Polygraph?

The police polygraph exam is a make-it-or-break-it moment for many aspiring police officers. It’s part of the comprehensive background check completed on all candidates when joining the police force. The polygraph exam involves an examiner from the Polygraph Unit strapping the candidate into the lie detector machine and conducting the test.

The polygraph instruments include two convoluted corrugated rubber tubes strapped across the candidate’s chest and abdomen, three sensors on their middle fingers, and a blood pressure cuff attached to the upper arm. These instruments connect to a control box that plugs into a software module on the examiner’s computer.

The polygraph machine measures the candidate’s vital signs as they answer questions. The examiner is looking for the stress response known as the “fight-or-flight” (FoF) mechanism launched by the sympathetic nervous system (SNS).

The SNS initiates the FoF when the candidate feels stressed because they have to lie to the examiner. This response elevates heart rate, respiration, and blood pressure while creating an electrical reaction in the skin and causing the subject to perspire. The polygraph picks up the changes in the candidate’s physical responses, presenting them to the polygraph examiner in chart format.


Why Does Law Enforcement Use the Polygraph?

The police polygraph aims to confirm the facts presented to the police department when applying for a position. The device helps the examiner determine if the candidate is lying about anything on their application or their intention to join the police services.

The results of the test are a determining factor in whether the candidate gets the job. If the lie detector test returns positive for “deception,” they won’t get an offer of employment from the police services.

This differs from most private sector companies that aren’t allowed to use polygraphs in hiring and firing. The “Employee Polygraph Protection Act of 1988” (EPPA) prevents private sector companies from implementing these exams in pre-employment screening. However, this isn’t the case in public-sector organizations involved in local, state, and federal law enforcement.

If the candidate fails, they aren’t at risk of prosecution, and the police department may not reveal the test results to any future employer. It’s interesting to note that the police polygraph is required for all jobs on the force, including sworn and non-sworn positions in their departments, including secretarial staff or dispatchers, and any law enforcement member with access to sensitive data and information.


What are the Types of Police Polygraphs?

When the candidate enters the exam room and the examiner wires them up to the polygraph, the test starts with the examiner conducting the “pre-test interview.” This test aims to ask the candidate basic questions regarding their personal history to use as control questions during the rest of the exam.

This process is known as the “Control Question Test” (CQT). After establishing a baseline for the candidate’s physiological response with the CQT, the examiner begins the second phase, known as the “Directed Lie Test” (DLT).

The DLT involves the examiner asking the candidate to lie about information so they can further establish a physiological response as a baseline. For instance, “have you ever climbed Mount Everest?” The candidate will answer using a lie, and the examiner checks the response created by the lie detector device.

The third and final stage of the police polygraph is the “Guilty Knowledge Test” (GKT). The GKT test is considered highly accurate at detecting deception in the candidate. It involves the candidate responding to the examiner’s questions in a yes-or-no format.


What are the Questions Asked on the Police Polygraph?

The examiner asks the candidate two types of questions during the police polygraph. The first type involves queries about specific incidents, such as have you broken the law in the last 24 hours?” The second type of question asked in the polygraph test involves broader questions such as, “Have you ever used illegal drugs?”

The examiner expects you to react more emotionally to the control question if you have nothing to hide. This occurs because the examinee might start thinking about the drugs they’ve used in the past and whether they count as illegal. Whereas the question of whether they have broken the law in the last 24 hours creates certainty in the examinee and less of an emotional response.

The police polygraph covers several topics and usually lasts around 90 minutes. Most of the questions asked during the exam revolve around the following categories.

  • Theft from an employer or shoplifting.
  • Illegal drug use, prescription drug misuse, and steroid use.
  • Illegal drug dealing or trafficking.
  • Alcohol use.
  • Minimization or falsification of information requested in the exam or background check process.
  • Participation in organized crime.
  • Arrests involve anything more serious than minor traffic violations.
  • Commission of crimes that are undetected by the police services.
  • Concealing anything in the candidate’s background that may affect their chances to obtain a position on the police force.
  • Involvement in physical fights with other people.
  • Involvement in domestic violence incidents.
  • Use of violence or excessive physical force against other people.
  • Receipt or payment of bribes.

The questions asked by the examiner revolve around the above categories. However, there may be several questions asked surrounding each section. If the polygraph examiner suspects deception during the exam, they may repeat a question to confirm their suspicions.

Here are some of the common questions asked by the examiner during the police polygraph test.

  • Did you intentionally withhold information on your employment application?
  • Did you lie or misrepresent information on your employment application?
  • Have you ever been fired from a previous job?
  • Have you falsified information on your background check?
  • Have you ever committed a crime where you weren’t arrested?
  • Have you ever been convicted of a crime involving domestic battery?
  • Have you used illegal drugs more than once a month in the last calendar year?
  • Have you used any other drugs other than cannabis in the previous 12 months?
  • Have you distributed cannabis or illegal drugs in the last three years?
  • Have you ever stolen over $500 worth of merchandise from an employer in a calendar year?
  • Have you ever been involved in a scheme to defraud a former employer?
  • Has your driver’s license ever been revoked or suspended?
  • Have you received more than one traffic citation in the last three years?
  • Have you lied about any of the questions in this exam?

The department will not hire you if you answer yes to any of the questions. If the examiner detects deception in any of your answers, they’ll repeat the question. If they continue to get a positive result for deception, the candidate fails the polygraph exam, and the police forces won’t hire them.

There might be some exceptions. For instance, if you haven’t smoked cannabis in the last three years or if you shoplifted when you were young. However, it’s critical to answer all questions honestly. The lie detector machine has an accuracy rate of between 87% and 97% at detecting deception, and you can’t control the fight-or-flight response the examiner picks up during the test.


How to Prepare for the Police Polygraph Exam

Successful preparation for the police polygraph ensures an optimal testing environment and a reduction in the chances of a false positive occurring. Read up about the test and understand everything you can about it before entering the exam room.

Avoid learning about “countermeasures” to fool the lie detector test while doing your research. The modern lie detector device can detect if you use countermeasures, and you’ll fail the test. Get a good night’s sleep the night before the exam. If you have trouble getting to sleep, listen to a guided meditation, and don’t use sleeping medication if you’re not used to it.

Avoid drinking too many cups of coffee or tea the morning of the test, as it stimulates your nervous system. The same applies to energy drinks. Drink water and ensure you have a meal in the morning to settle your nervous system.

With these tips, you’ll pass the police polygraph, provided you have nothing to hide.