Polygraph Field Examinations: On-Site Testing Guide

Defining the Field Examination

A polygraph field examination is a lie detector test conducted at any location other than the examiner's permanent office or dedicated polygraph suite. The term "field" refers to the testing being brought to the examinee or to a location convenient for the requesting party, rather than requiring the examinee to travel to a fixed polygraph facility.

Field examinations are far more common than most people realise. Law enforcement agencies frequently conduct polygraph testing in station interview rooms, federal agencies use secure facility conference rooms, and private examiners travel to corporate offices, attorney conference rooms, hotel suites, and rented office spaces to perform examinations. Federal agencies such as the FBI, CIA, and NSA regularly conduct examinations through their own trained examiners who completed training at the National Center for Credibility Assessment (NCCA) [1]Verified NCCA Federal Examiner Training and Requirements
Confirms NCCA trains federal polygraph examiners for agencies including FBI, CIA, and NSA.

The critical point for examinees to understand is that a field examination is not a lesser version of an office-based test. When conducted properly by a qualified examiner following APA Standards of Practice, a field examination uses the same instruments, follows the same protocols, employs the same validated questioning techniques, and applies the same scoring algorithms as any test conducted in a purpose-built polygraph room. The APA Standards of Practice require that examiners use evidence-based validated testing techniques regardless of testing location [2]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA testing environment must be reasonably free from distractions; audio/video recording requirements; validated technique requirements; and acquaintance test requirements apply to all examination locations. Book a polygraph test with confidence, knowing that on-site examinations meet the same rigorous standards.

Operational and Practical Reasons for On-Site Testing

Field examinations serve a wide range of practical needs that make them indispensable across law enforcement, corporate, legal, and clinical settings. The most common reasons include:

Security requirements: Federal agencies and military installations often cannot allow outside personnel to bring equipment into classified spaces, necessitating the use of agency-owned field equipment in secure rooms. The Department of Defense Instruction 5210.91 governs polygraph and credibility assessment procedures, including field deployments for Preliminary Credibility Assessment Screening System (PCASS) examinations [3]Verified DoDI 5210.91 — Polygraph and Credibility Assessment Procedures
Confirms Department of Defense procedures for polygraph and credibility assessment examinations including field deployment of PCASS instruments.

Examinee logistics: When the examinee cannot travel — due to incarceration, hospitalisation, disability, or geographic remoteness — the examiner brings the test to them. Defence attorneys frequently arrange field examinations for clients held in detention facilities.

Workplace investigations: During active theft, fraud, or misconduct investigations, employers may need multiple employees tested at the work site to minimise disruption and maintain confidentiality. Post-conviction sex offender testing (PCSOT) is another common field application, where examinations are conducted at treatment or probation facilities.

Time sensitivity: Criminal investigations sometimes require rapid polygraph results, and travelling to a fixed facility may cause unacceptable delays.

Common Requestors and Their Needs

Law enforcement agencies are among the most frequent users of field polygraph testing. Police departments, sheriffs' offices, and federal investigative agencies routinely conduct examinations in station interview rooms or temporary field offices. Federal examiners utilise Lafayette systems (including the LX6) for pre-employment screening examinations conducted at various field locations [4]Verified Federal Contract Polygraph Examiner Requirements (USSS)
Confirms federal examiners use Lafayette LX6 systems for field-deployed pre-employment polygraph examinations at various locations.

Defence attorneys and law firms regularly arrange field examinations at their offices or nearby conference facilities. These tests help evaluate a client's claims prior to trial strategy decisions, and the results — while governed by jurisdiction-specific admissibility rules — can provide powerful leverage in plea negotiations.

Corporate security departments request on-site testing during workplace theft or fraud investigations. Private employers must comply with the Employee Polygraph Protection Act (EPPA) of 1988, which generally prevents most private-sector employers from requiring polygraph tests [5]Verified Employee Polygraph Protection Act of 1988 — Wikipedia
Confirms EPPA generally prevents private employers from using polygraph tests with exemptions for government agencies, security firms, and pharmaceutical companies. However, EPPA provides exemptions for security services firms, pharmaceutical companies handling controlled substances, and employers investigating specific incidents of economic loss [6]Verified 29 CFR Part 801 — Application of the Employee Polygraph Protection Act of 1988
Confirms EPPA exemptions for security services, controlled substances employers, and ongoing economic loss investigations.

Military commands, intelligence agencies, probation departments, and treatment providers all conduct field examinations as part of their routine operations. The APA, established in 1966, serves as the world's leading association in this field, with over 2,700 members worldwide who follow its Standards of Practice [7]Verified American Polygraph Association — About
Confirms APA was established in 1966 as the world's leading polygraph association with over 2,700 members.

Modern Portable Polygraph Instruments

Today's polygraph instruments are specifically engineered for portability and field reliability. The four major manufacturers produce compact, USB-powered data acquisition units that an examiner can carry in a backpack or small case alongside a laptop and sensor kit.

Lafayette Instrument Company produces the LX6 and LX7 systems. The LX6 features 10 data channels, Fischer connectors, and 32-bit analog-to-digital conversion [8]Verified Lafayette LX6 Polygraph System — Product Page
Confirms LX6 features 10 data channels, Fischer connectors, USB-powered operation, and ASTM compliance. The LX7 is Lafayette's next-generation system designed to "elevate accuracy, consistency, and usability in the field" [9]Verified Lafayette LX7 Polygraph System — Product Page
Confirms LX7 is Lafayette's next-generation system designed for accuracy, consistency, and field usability. Both systems are USB-powered and meet ASTM standards. Lafayette's LXEdge software is compatible with both the LX6 and LX7 as well as the Limestone Paragon series [10]Verified LXEdge Software Compatibility
Confirms LXEdge is compatible with Lafayette LX6, LX7, and Limestone Paragon series; confirms LX7 specs including 32-bit resolution, 180 sps, USB power, and 5000Vrms isolation. For detailed guidance on selecting equipment, see our guide on polygraph hardware vs. software investment decisions.

Stoelting Company has manufactured polygraph instruments since 1930 and introduced its Computerized Polygraph System (CPS) in 1992 [11]Verified Stoelting Company — Our Company
Confirms Stoelting created its first Cardio-Pneumo Polygraph in 1935, introduced CPS in 1992, and released the world's first all-electronic polygraph in 1974. The current-generation CPS Elite features an LCD touchscreen with CPS Fusion software, sampling at 360 samples per second for EDA channels, and draws all power from a USB connection [12]Verified Stoelting CPS Elite Polygraph Systems — Product Page
Confirms CPS Elite features LCD touchscreen, CPS Fusion software, 360 sps EDA sampling, and USB power; Stoelting has manufactured polygraph instruments since 1930. Its built-in display is unique in the industry, providing active feedback mirrored from the software.

Limestone Technologies (now a Lafayette subsidiary following the August 12, 2022 acquisition [13]Verified Lafayette Instrument Co. Acquires Limestone Technologies
Confirms Lafayette acquired Limestone Technologies on August 12, 2022; Lafayette established in 1947) produces the ParagonX system, offering high-retention USB connectivity with dual-channel 32-bit data acquisition [14]Verified Limestone Technologies ParagonX — Product Page
Confirms ParagonX offers high-retention USB to dual channel 32-bit data acquisition for professional polygraph examiners.

Axciton Systems was the first company to produce a usable computerised polygraph system, with over 25 years of experience in the field [15]Verified Axciton Systems, Inc. — Official Website
Confirms Axciton was the first company to produce a usable computerised polygraph system with over 25 years of experience. The Axciton Sensor Box offers 24-bit resolution, USB power, 5–8 channel configurations, and up to 2,000 samples per second capability.

All of these systems are designed to perform identically whether set up in a purpose-built polygraph suite or a temporary field location. Scoring algorithms such as PolyScore and CPS operate on the same mathematical principles regardless of where the data is collected.

Complete Field Kit Components

A typical field polygraph kit includes the data acquisition unit, a laptop computer with examination software, two pneumograph assemblies (thoracic and abdominal), a blood pressure cuff with pump, electrodermal activity (EDA) sensors, a seat activity sensor, a photoplethysmograph (PPG) finger clip, an audio or audio-video recording device, and cables and accessories stored in a protective carrying pouch [16]Verified Lafayette Instrument Company — Products (Accessories)
Confirms Lafayette product line including LX7, LX6, ParagonX systems, protective pouches, and backpacks for field transport.

Lafayette offers branded backpacks that fit laptops up to 16 inches along with dedicated storage cases for LX6/LX7 accessories [17]Verified Lafayette LX6/LX7 Accessories and Storage Cases
Confirms Lafayette-branded backpacks for laptops up to 16 inches and portable storage cases for LX6/LX7 accessories. The total kit weight — including laptop, sensors, camera, and accessories — typically ranges from 5 to 10 kg, making it easily transportable by a single examiner.

Environmental Requirements

The APA Standards of Practice (amended August 23, 2024) establish clear requirements that apply equally to office and field examinations. The foundational requirement states: "The testing environment should be reasonably free from distractions" [2]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA testing environment must be reasonably free from distractions; audio/video recording requirements; validated technique requirements; and acquaintance test requirements apply to all examination locations. This single standard encompasses several practical considerations that examiners must evaluate before proceeding with any field test.

The room must provide adequate privacy — only the examiner and examinee should be present during data collection. Manageable noise levels are essential; ambient sounds from adjacent offices, traffic, or building systems must not be so loud as to startle the examinee or mask the examiner's questions. Temperature should be comfortable and stable, as extremes of heat or cold can produce physiological artefacts that degrade data quality.

Furniture must be stable — a wobbly chair can produce movement artefacts that contaminate pneumograph and activity-sensor data. The examination chair and desk should remain stationary throughout testing. Freedom from electromagnetic interference is important because strong EMI sources can introduce electrical noise into sensor channels.

The APA also requires that an audio or audio-video recording of all phases of the examination be maintained as part of the examination files for a minimum of one year [2]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA testing environment must be reasonably free from distractions; audio/video recording requirements; validated technique requirements; and acquaintance test requirements apply to all examination locations. Field examiners must ensure their recording equipment functions properly in the chosen venue. Furthermore, examiners must conduct an acquaintance test for all diagnostic, evidentiary, paired-testing, initial screening, and initial investigative examinations, regardless of venue [2]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA testing environment must be reasonably free from distractions; audio/video recording requirements; validated technique requirements; and acquaintance test requirements apply to all examination locations.

The International Society of Polygraph Examiners (ISOPE) maintains similar standards, referencing ASTM E2062, which establishes essential elements in PDD examination procedures [18]Verified ASTM E2062-11(2017) Standard Guide for PDD Examination Standards of Practice
Confirms ASTM E2062 establishes essential elements in PDD examination procedures referenced by ISOPE and other international bodies. These international standards reinforce that field conditions must meet the same benchmarks as office testing.

Practical Differences Between Testing Environments

While the scientific protocols, instruments, and scoring methods are identical, several practical differences distinguish field and office examinations.

Setup time: Office-based examiners typically have instruments permanently connected and calibrated. Field examiners must unpack, connect, calibrate, and test all equipment on arrival, adding 15–30 minutes to the appointment.

Environmental control: A dedicated polygraph room is purpose-designed with controlled lighting, temperature, climate-controlleding, and stable furniture. Field locations vary widely — an examiner may encounter a well-equipped corporate boardroom one day and a noisy police station interview room the next. Professional examiners assess conditions before proceeding and will postpone testing if the environment is inadequate.

Cost: Field examinations typically cost more than office-based tests. Specific-issue polygraph examinations generally range from $500 to $1,500 depending on complexity, examiner experience, and location [19]Verified Average Polygraph and Lie Detector Test Cost
Confirms specific-issue polygraph exam costs between $500 and $1,500 depending on complexity, issue type, and travel time. Field examinations may carry a premium to cover the examiner's travel time, mileage, setup effort, and potential venue rental costs. Always confirm the total cost before scheduling by reviewing our polygraph test prices.

Recording logistics: In an office, cameras and microphones are permanently mounted. Field examiners must position recording equipment in an unfamiliar room, ensuring adequate audio and video coverage as required by APA standards.

Examinee comfort: Some examinees feel more comfortable testing in a familiar environment — their attorney's office, for example — which can reduce test anxiety and contribute to cleaner physiological baselines. Others may find the formality of a dedicated testing facility more reassuring. Either way, the examiner's professional manner and thorough pre-test interview are the most important factors in establishing rapport.

From Arrival to Results

A standard polygraph examination, whether in the field or the office, can be divided into at least three core components: the pre-test interview, the question procedure (data collection), and the post-test interview [20]Verified Scientific Validity of Polygraph Testing (OTA Chapter 2)
Confirms polygraph examination takes 1–3 hours and is divided into pre-test interview, question procedure, and post-test interview; pre-test is indispensable component. The field examination adds an initial setup phase:

Step 1 — Venue Assessment and Setup (15–30 minutes): The examiner arrives early, inspects the room for noise, temperature, privacy, furniture stability, and electromagnetic interference. Equipment is unpacked, the data acquisition unit is connected to the laptop via USB, sensors are tested, and audio/video recording begins.

Step 2 — Pre-test Interview (30–60 minutes): The examiner completes required paperwork, obtains the examinee's informed and voluntary consent, and discusses the test. During this phase, the examiner reviews the examinee's medical and psychological suitability for testing, explains the instruments, and develops and reviews the specific test questions with the examinee [21]Verified APA Polygraph Frequently Asked Questions
Confirms pre-test interview procedures, EPPA exemptions, and jurisdictional variation in polygraph admissibility. The pre-test interview has been called "an indispensable component of the polygraph examination" [20]Verified Scientific Validity of Polygraph Testing (OTA Chapter 2)
Confirms polygraph examination takes 1–3 hours and is divided into pre-test interview, question procedure, and post-test interview; pre-test is indispensable component.

Step 3 — Sensor Attachment and Acquaintance Test (10–15 minutes): Pneumograph tubes are placed around the chest and abdomen, the blood pressure cuff is positioned on the upper arm, EDA sensors are applied to the fingers, the PPG clip is placed on a finger, and the activity sensor is positioned on the chair. The examiner then conducts an acquaintance (or stimulation) test to demonstrate the instrument's sensitivity.

Step 4 — In-Test Data Collection (30–45 minutes): The examiner administers 3–5 chart presentations of the validated question sequence. Each chart runs approximately 5–8 minutes with rest periods between presentations. APA standards require a minimum of 20 seconds from question onset to question onset [2]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA testing environment must be reasonably free from distractions; audio/video recording requirements; validated technique requirements; and acquaintance test requirements apply to all examination locations.

Step 5 — Post-Test Analysis and Discussion (15–30 minutes): The examiner reviews the physiological data using both manual scoring and computerised scoring algorithms. Results are discussed with the examinee, and any admissions or clarifications are documented.

The total appointment time is typically 90 to 150 minutes, though field examinations may run slightly longer due to the added setup phase.

What the Research Shows About Field Polygraph Accuracy

Field polygraph accuracy has been extensively studied, and the research consistently demonstrates that properly conducted field examinations achieve strong accuracy rates.

The APA's landmark 2011 meta-analytic survey examined 38 studies satisfying rigorous qualitative and quantitative requirements. These studies included 295 scorers who provided 11,737 scored results from 3,723 examinations. The data showed that event-specific (single-issue) diagnostic testing achieved an aggregated decision accuracy of 89% (confidence interval: 83%–95%), with an estimated inconclusive rate of 11% [22]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms event-specific diagnostic accuracy of 89% (CI: 83–95%), overall decision accuracy of 87% (CI: 80–94%), and 13% inconclusive rate across validated techniques. Multiple-issue testing produced 85% accuracy (CI: 77%–93%), and the combination of all validated PDD techniques yielded 87% overall decision accuracy (CI: 80%–94%) with a 13% inconclusive rate [22]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms event-specific diagnostic accuracy of 89% (CI: 83–95%), overall decision accuracy of 87% (CI: 80–94%), and 13% inconclusive rate across validated techniques.

The 1997 APA-commissioned review of 12 field validity studies conducted since 1980 found CQT accuracy in real-life applications ranged from 92% to 98% [23]Verified Review of 12 Field Validity Studies of CQT
Confirms APA-commissioned review of 12 field validity studies found CQT accuracy in real-life applications ranged from 92%–98%. This review was based on studies involving actual criminal investigations, not laboratory simulations, making the results particularly relevant to real-world field conditions.

A pivotal field study by Ginton (2012) demonstrated 94% accuracy for detecting deceptive examinees and 83.5% accuracy for truthful examinees when excluding inconclusive outcomes [24]Verified A non-standard method for estimating the accuracy of lie detection techniques demonstrated on a self-validating set of field polygraph examinations
Confirms 94% accuracy for detecting deceptive examinees and 83.5% for truthful examinees in field conditions, excluding 20% inconclusives. This research used a self-validating methodology that strengthened confidence in the accuracy figures.

The Horvath and Reid (1982) field validity study was one of ten field studies meeting OTA minimum scientific standards, providing accuracy data from real criminal investigations [25]Verified Field Validity Study of CQT
Confirms this was one of ten field studies meeting OTA minimum scientific standards, providing accuracy data from real criminal investigations. Similarly, Barland and Raskin (1976) conducted one of the earliest rigorous field studies of the CQT with criminal suspects, establishing baseline accuracy data referenced in every subsequent government review [26]Verified Validity and Reliability of Polygraph Examinations of Criminal Suspects
One of the earliest rigorous field studies of CQT with criminal suspects, establishing baseline accuracy data referenced in every subsequent government review.

Research by Matte and Reuss (1992) found that the lower pneumograph was the most productive respiratory measure in 51% of field cases, supporting the importance of dual pneumograph recording in field settings [27]Verified A Study of the Relative Effectiveness of Physiological Data in Field Polygraph Examinations
Confirms the lower pneumograph was the most productive respiratory measure in 51% of field cases, supporting dual pneumograph recording in field settings. This finding has direct implications for field testing, as it confirms the value of recording both thoracic and abdominal respiration — a standard feature of all modern portable instruments.

Harwell (2000) demonstrated that the 3-position scoring scale achieved criterion accuracy significantly greater than chance in field examinations, with no significant differences compared to the 7-position model [28]Verified A comparison of 3- and 7-position scoring scales with field examinations
Confirms both 3-position and 7-position scoring scales demonstrate criterion accuracy significantly greater than chance in field examinations. This research validates the scoring approaches commonly used in field settings.

The research base for field polygraph accuracy extends further through additional studies. Honts and Raskin (1988) conducted the first field validation of the directed-lie comparison question, finding it at least as accurate as the probable-lie CQT with fewer false positive errors [29]Verified A Field Study of the Validity of the Directed Lie Control Question
Confirms first field validation of directed-lie comparison question, finding DLC at least as accurate as probable-lie CQT with fewer false positives. Ginton (2017) provided field evidence for the practical effectiveness of both exclusive and non-exclusive comparison questions in real criminal investigations [30]Verified Examining Different Types of Comparison Questions in a Field Study of CQT Polygraph Technique
Confirms field study evidence for the practical effectiveness of both exclusive and non-exclusive comparison questions in real criminal investigations. Ginton (2019) contributed foundational research on built-in validity in field polygraph examinations [31]Verified A Built-In Validity in Polygraph Field Examinations
Foundational research relevant to field polygraph examination validity methodology.

Factors That Can Affect Field Accuracy

While the accuracy figures above are encouraging, several field-specific factors can influence results. Environmental noise that startles the examinee can produce artefacts in physiological data. Temperature extremes may alter baseline skin conductance readings. Interruptions from external sources can disrupt the psychological set necessary for valid testing.

These risks are precisely why APA standards require the testing environment to be reasonably free from distractions [2]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA testing environment must be reasonably free from distractions; audio/video recording requirements; validated technique requirements; and acquaintance test requirements apply to all examination locations. A competent examiner will identify and mitigate these factors before testing begins. If conditions cannot be adequately controlled, a professional examiner will postpone the examination rather than proceed with compromised data quality.

The British Psychological Society Working Party (2004) reviewed the scientific evidence base across multiple polygraph applications and provided recommendations for UK adoption, recognising that field-condition polygraph testing has meaningful utility when properly conducted [32]Verified A Review of the Current Scientific Status and Fields of Application of Polygraphic Deception Detection
Official UK scientific assessment by the British Psychological Society reviewing evidence base across multiple polygraph applications. Conditions such as bipolar disorder or menopause may require additional examiner consideration, but do not automatically preclude valid field testing.

Where Field Examinations Typically Take Place

Law enforcement interview rooms are the most common field testing venue. These rooms are typically designed for interrogation and generally meet polygraph requirements — they are private, quiet, temperature-controlled, and equipped with recording capability. Many police departments have dedicated polygraph rooms within their facilities.

Corporate offices and conference rooms are frequently used for workplace investigations. These venues usually offer good environmental control, stable furniture, and privacy. The examiner should ensure that phone lines are silenced, nearby staff are informed not to interrupt, and building maintenance activities (such as loud HVAC cycling) are minimised during the test window.

Attorney conference rooms provide a familiar, controlled setting for defence examinations. Many law firms have well-appointed conference rooms that meet or exceed the environmental requirements for polygraph testing.

Hotel business centres and rented office spaces offer neutral territory when neither the examiner's office nor the examinee's location is practical. Professional examiners often have preferred venues in different cities where they know the rooms meet testing standards.

Military installations and federal facilities have their own protocols for field testing. Federal examiners conduct examinations at various locations nationwide, utilising agency-provided Lafayette systems [4]Verified Federal Contract Polygraph Examiner Requirements (USSS)
Confirms federal examiners use Lafayette LX6 systems for field-deployed pre-employment polygraph examinations at various locations. The NCCA provides continuing education programmes that include platform-specific training for Axciton, Lafayette, and Limestone systems [33]Verified NCCA Continuing Education Program — Computerised Polygraph Courses
Confirms NCCA provides separate training courses for Axciton, Lafayette, and Limestone polygraph systems for federal examiners.

Probation offices and treatment facilities are common venues for PCSOT examinations, where sex offenders are tested as part of supervision and treatment programmes. These field examinations play a vital role in community safety. Check our polygraph test locations for available testing venues near you.

Preparation for Examinees

Your preparation for a field polygraph is the same as for any polygraph examination. Get a good night's sleep the night before. Eat normally — avoid skipping meals, as low blood sugar can affect physiological readings. Avoid excessive caffeine, as it can elevate heart rate and skin conductance baselines. Take any prescribed medications as usual — stopping medications before a test can be medically dangerous and may also affect your physiology. Wear comfortable, loose-fitting clothing.

If you have medical conditions, psychological diagnoses, or are taking medications that may affect your physiology, inform the examiner during the pre-test phase. A professional examiner will assess your suitability for testing and may adjust procedures accordingly.

Do not research so-called "countermeasure" techniques online. Federal agencies specifically advise against seeking polygraph information from unofficial internet sources [34]Verified TSA Polygraph Examination Information
Confirms federal agencies advise against seeking polygraph information from unofficial internet sources. Attempting countermeasures is detectable by modern instruments and trained examiners, and it can turn what would have been a truthful result into a deceptive or inconclusive outcome. Learn more about the risks of manipulated results in our guide on fake polygraph results and how to verify authenticity.

Preparation for Venue Arrangers

If you are arranging the venue for a field examination — as an attorney, employer, or case manager — ensure the room meets the following criteria:

Privacy: The room should have a solid door that closes completely. Glass walls should have blinds or coverings. Only the examiner and examinee should be in the room during data collection.

Quiet: The room should be away from high-traffic areas, break rooms, and external noise sources. Turn off nearby radios, televisions, and speaker systems.

Temperature control: The room should be set to a comfortable temperature (approximately 20–22°C / 68–72°F) at least 30 minutes before the examination begins. The HVAC system should maintain a consistent temperature without loud cycling.

Furniture: Provide a stable desk or table and a firm, stationary chair for the examinee. Avoid swivel chairs, rolling chairs, or chairs with arms that might interfere with sensor placement.

Power and connectivity: Ensure at least one accessible electrical outlet for the examiner's laptop. While modern polygraph instruments are USB-powered and do not require separate mains power, the laptop will need to be plugged in for the full 2–3 hour session.

Duration: Block the room for a minimum of three hours to allow for setup, the full examination, and teardown. Inform building security or reception that the room must not be disturbed during this period.

Admissibility of Field Polygraph Results

The admissibility of polygraph evidence varies by jurisdiction. In the landmark 1998 case United States v. Scheffer (523 U.S. 303), the Supreme Court ruled that Military Rule of Evidence 707, which makes polygraph evidence inadmissible in court-martial proceedings, does not unconstitutionally abridge the right of accused members of the military to present a defence [35]Verified United States v. Scheffer, 523 U.S. 303 (1998)
Confirms the first Supreme Court ruling on polygraph testing; held that per se exclusion of polygraph evidence in military courts does not violate Sixth Amendment right to present a defence. This was the first case in which the Supreme Court issued a ruling regarding polygraph testing [35]Verified United States v. Scheffer, 523 U.S. 303 (1998)
Confirms the first Supreme Court ruling on polygraph testing; held that per se exclusion of polygraph evidence in military courts does not violate Sixth Amendment right to present a defence.

The Scheffer decision left it to individual jurisdictions to determine polygraph admissibility in civilian courts. Some federal courts of appeal have abandoned the per se rule excluding polygraph evidence, leaving admissibility to judicial discretion [35]Verified United States v. Scheffer, 523 U.S. 303 (1998)
Confirms the first Supreme Court ruling on polygraph testing; held that per se exclusion of polygraph evidence in military courts does not violate Sixth Amendment right to present a defence. Some states allow polygraph evidence when both parties agree in advance (stipulated admissibility), and New Mexico allows polygraph evidence even without both parties agreeing [36]Verified Do 'lie detectors' work? What psychological science says about polygraphs
Confirms about half of US states allow polygraph evidence by stipulation and New Mexico allows it without both parties agreeing.

Critically, field-conducted tests are treated no differently than office-conducted tests for admissibility purposes. What matters is the examiner's compliance with professional standards, the use of validated techniques, and the quality of the examination — not the physical location where it was performed.

Employee Rights Under EPPA

The Employee Polygraph Protection Act (EPPA) of 1988 prohibits most private employers from using lie detector tests either for pre-employment screening or during the course of employment [5]Verified Employee Polygraph Protection Act of 1988 — Wikipedia
Confirms EPPA generally prevents private employers from using polygraph tests with exemptions for government agencies, security firms, and pharmaceutical companies. Federal, state, and local government employers are exempt from EPPA [5]Verified Employee Polygraph Protection Act of 1988 — Wikipedia
Confirms EPPA generally prevents private employers from using polygraph tests with exemptions for government agencies, security firms, and pharmaceutical companies.

EPPA does permit polygraph tests (but no other types of lie detector tests) under limited circumstances: employers whose primary business is providing security services such as armored car personnel, security alarm systems, or uniformed security personnel; employers authorised to manufacture, distribute, or dispense controlled substances; and employers conducting ongoing investigations involving economic loss or injury such as theft, embezzlement, or sabotage [6]Verified 29 CFR Part 801 — Application of the Employee Polygraph Protection Act of 1988
Confirms EPPA exemptions for security services, controlled substances employers, and ongoing economic loss investigations.

Where testing is legally permitted under EPPA, the venue — whether an office or field location — does not change the examinee's legal rights. All EPPA protections, including the right to terminate the test at any time, apply equally in field settings. For comprehensive information about your workplace rights, visit our employee rights and EPPA guide.

Warning Signs of Inadequate Field Conditions

A professional examiner will assess venue conditions before proceeding. However, examinees and venue arrangers should also be aware of conditions that may compromise data quality:

Excessive ambient noise: Construction work, loud HVAC systems, traffic noise, or adjacent conversations that can be heard clearly through walls. These sounds can produce startle responses that contaminate physiological data.

Lack of privacy: Glass-walled rooms without coverings, rooms where others can enter without warning, or spaces with security cameras visible to the examinee that may cause self-consciousness and elevated arousal.

Temperature extremes: Rooms that are too hot or too cold can cause physiological changes — sweating, shivering, or vasoconstriction — that interfere with EDA and cardiovascular readings.

Unstable furniture: Wobbly tables, swivel chairs, or chairs on wheels can generate movement artefacts that contaminate pneumograph, cardio, and activity-sensor channels.

Electromagnetic interference: Proximity to high-voltage electrical panels, server rooms, MRI machines, or large industrial equipment can introduce electrical noise into sensor channels.

Interruptions: Phones ringing, people knocking on the door, fire alarms, or PA system announcements all disrupt the psychological set of the examination.

A competent examiner will postpone or reschedule the examination rather than proceed under conditions that could compromise results. Examinees should not hesitate to raise environmental concerns — a professional examiner welcomes such questions because they demonstrate a shared commitment to accuracy. For guidance on identifying qualified examiners and avoiding substandard practices, see our article on continuing education requirements for polygraph examiners.

Leading Manufacturers and Their Field-Ready Systems

Lafayette Instrument Company, established in 1947, is the world's leading manufacturer of polygraph instrumentation [37]Verified Lafayette Instrument Company — Our Story
Confirms Lafayette was established in 1947 and acquired Limestone Technologies in 2022. The company acquired Limestone Technologies on August 12, 2022, expanding its product line and international reach [13]Verified Lafayette Instrument Co. Acquires Limestone Technologies
Confirms Lafayette acquired Limestone Technologies on August 12, 2022; Lafayette established in 1947. Lafayette currently offers the LX6, LX7, and ParagonX (via Limestone) systems, all of which are USB-powered and designed for field portability. The LX7 features 32-bit analog-to-digital conversion, 180 samples per second across all channels, 5000Vrms isolation on all channels, and an ABS/polycarbonate blend enclosure measuring just 8.66" x 3.61" x 1.21" [38]Verified Lafayette LX7 Polygraph System Upgrade Specifications
Confirms LX7 specifications: 8.66 x 3.61 x 1.21 inches, USB power, 5000Vrms isolation, 32-bit resolution, 180 sps, ABS/polycarbonate blend enclosure, ASTM compliant, CE certified. Lafayette's LXSoftware is bundled with the Objective Scoring System (OSS-3) scoring algorithm [39]Verified LXSoftware with OSS-3
Confirms LXSoftware is bundled with the Objective Scoring System (OSS-3) scoring algorithm and is compatible with LX4000, LX5000, LX6, and LX7 systems.

Stoelting Company has been manufacturing polygraph instruments since 1930 and introduced the Computerised Polygraph System (CPS) in 1992 [11]Verified Stoelting Company — Our Company
Confirms Stoelting created its first Cardio-Pneumo Polygraph in 1935, introduced CPS in 1992, and released the world's first all-electronic polygraph in 1974. Today's CPS Elite features a built-in LCD touchscreen — the only polygraph with this capability — CPS Fusion software, 360 samples per second EDA sampling, and USB power [12]Verified Stoelting CPS Elite Polygraph Systems — Product Page
Confirms CPS Elite features LCD touchscreen, CPS Fusion software, 360 sps EDA sampling, and USB power; Stoelting has manufactured polygraph instruments since 1930. Stoelting's long history includes creating the first cardio-pneumo polygraph in 1935 and releasing the world's first all-electronic polygraph in 1974 [40]Verified Stoelting Company — History of Polygraph Innovation
Confirms Stoelting created first Cardio-Pneumo Polygraph in 1935, released world's first all-electronic polygraph (Polyscribe) in 1974, and introduced CPS in 1992.

Axciton Systems was the first company to produce a usable computerised polygraph system [15]Verified Axciton Systems, Inc. — Official Website
Confirms Axciton was the first company to produce a usable computerised polygraph system with over 25 years of experience. Their Sensor Box packages offer 24-bit resolution, USB power, 5–8 channel configurations, and up to 2,000 samples per second capability — the highest sampling rate in the industry.

All four manufacturers' systems (including the Limestone ParagonX) produce portable, USB-powered instruments that meet ASTM standards and are fully suitable for field deployment. The NCCA provides specific training courses for Axciton, Lafayette, and Limestone systems for federal examiners [33]Verified NCCA Continuing Education Program — Computerised Polygraph Courses
Confirms NCCA provides separate training courses for Axciton, Lafayette, and Limestone polygraph systems for federal examiners. Examiners interested in comparing these platforms should consult our guide on polygraph hardware vs. software investment.