Where the polygraph fits in the police hiring process
In departments that use it, the polygraph is usually one step in a longer sequence that also includes written tests, a physical agility test, a psychological exam, a medical exam and a background investigation. The exact order varies. A common arrangement puts the polygraph after the physical test and before the psychological exam.
It is a screening exam. The examiner is not investigating a specific crime. The exam is meant to check whether what you wrote in your application and background packet is complete and truthful, and it usually focuses on your own past conduct. Professional guidance describes it as one decision-support tool that should be weighed with other information, not the only basis for hiring or rejecting someone.
Not every department uses one. A 1995 survey found 62% of large agencies and 13% of small ones did, and practices have changed since. Ask the recruiter whether yours does.
What the exam usually covers
Each department sets its own topics, but they tend to cluster around the same areas. The list below describes common themes, not a script.
| Area | What it usually touches |
|---|---|
| Criminal history | Serious offenses, whether or not you were charged, and anything you did not disclose on the forms. |
| Drug use | Illegal drug use, often with a focus on recent years. Departments set different thresholds. |
| Discipline and work history | Being fired or disciplined, especially for dishonesty or misconduct. |
| Violence and conduct | Domestic violence and other serious misconduct as an adult. |
| Honesty on your application | Whether your forms and interviews so far were accurate and complete. |
The examiner reviews each question with you before the charts begin. That is the time to ask what a question means and how far back it reaches. For how the exam is structured, see how a polygraph runs, step by step, and for the pre-test conversation, what happens in the pre-test interview.
Common disqualifiers
Disqualifiers vary by department, and most are decided in the background investigation, not by the polygraph alone. Commonly cited ones include certain criminal convictions, domestic violence convictions, drug use above the department's limits, a poor driving record, being fired for dishonesty and a dishonorable military discharge.
Do the rules protect you?
The federal Employee Polygraph Protection Act, which restricts most private employers, excludes federal, state and local governments. In practice that generally means police applicants do not have its protections, although the Department of Labor fact sheet does not address police specifically and some states or cities have their own rules. Check the rules for your location.
Even where the Act does not apply, the same basic ideas show up in good practice: you should be told what the exam covers, results should be kept confidential, and you should be able to raise a medical condition or ask for a question to be clarified. For private employers and your rights more generally, see polygraphs in the workplace.
How to prepare, honestly
- Get your background packet right first.Reread every form. Fix errors and gaps before the exam, and tell the investigator about anything you realize you left out.
- Know what you will be asked.Ask the recruiter about the process and the topics. Understanding the format removes most of the surprise.
- Be specific, not perfect.If you are unsure about a date or detail, say so. Do not guess to fill a gap.
- Disclose health and medication.Tell the examiner about conditions, medication, pain or poor sleep before the charts begin. See how medical conditions affect polygraphs.
- Clarify every question.Ask for any unclear wording to be explained and agree it before the charts.
- Look after the basics.Sleep, eat normally and avoid unusual substances. Answer plainly, at a natural pace.
We do not teach countermeasures. Examiners are trained to look for them, and being flagged can end an application even when you were honest. See why tricks backfire.
If it goes badly
Your options depend on the department. Ask what an inconclusive or failed result means for your application, whether a retest or interview is possible, and who decides. Write down what happened while it is fresh. The National Research Council found polygraph accuracy is well above chance but far from perfect, and that anxiety about being tested can distort results, so a bad result is an opinion on your charts, not a verdict.
Read what an inconclusive result means and what to do if you failed while telling the truth. If the job is a federal one, see our guides on the CBP polygraph and TS/SCI clearance polygraphs.
This guide is general information, not legal advice. Policies differ between departments.
Frequently asked questions
Do all police departments use a polygraph?
Is it legal for a police department to require a polygraph?
What happens if I fail the police polygraph?
Can I retake the police polygraph?
What if I forgot to put something on my background forms?
Can nerves make an honest applicant fail?
Sources
- US Department of Labor: Fact Sheet #36, Employee Polygraph Protection Act
- Polygraph (1995): national survey of practices and policies on pre-employment polygraph screening in police agencies (NCJRS abstract)
- American Polygraph Association: Pre-employment polygraph screening
- Go Law Enforcement: Police officer background investigation
- National Research Council: The Polygraph and Lie Detection, executive summary (2003)
Applying to a police department and want to walk in prepared?
In a private 1-on-1 session we go through the process, the kinds of questions, how to handle the pre-test interview and how to answer clearly and honestly. We do not teach countermeasures.