What are the uses of polygraphs in espionage investigations?

Lie detector test has been used by government agencies and law enforcement for decades as a tool in investigations and vetting processes. Though controversial, polygraphs remain routine in criminal cases and for screening personnel who will handle sensitive national security information.

A polygraph instrument monitors and records several physiological indicators, including blood pressure, pulse, respiration, and skin conductivity as a subject answers questions. The underlying theory is that deception will produce measurable increases in anxiety and stress responses. Though not universally accepted as 100% reliable, proponents argue polygraphs accurately detect lies at rates above 90% in trained examiners’ hands.

Shortly after their introduction in the 1920s, polygraphs were adopted by law enforcement. Early on, the technology drew interest from intelligence agencies as well. A polygraph was used by the CIA, NSA, and FBI in the mid-20th century to uncover leaks and defectors. The Cold War era was filled with high-profile espionage cases involving polygraphs. Aldrich Ames, the CIA officer who spied for the Soviets in the 1980s and 90s, repeatedly beat the machine during employment screening exams. Some experts believe Ames’ success helped spur efforts to improve polygraph techniques.

CIA officer turned Soviet mole Robert Hanssen failed a 1979 polygraph focused on the unexplained income he had from selling secrets. Though Hanssen temporarily ended his espionage, he managed to convince investigators of an innocent explanation. He resumed spying for the Russians in 1985 and eluded capture for 15 more years. The Hanssen and Ames cases illustrate the ongoing debate about the reliability of polygraphs in catching spies and other national security threats.

Despite accuracy concerns, polygraphs remain important tools for intelligence and law enforcement agencies.

• Pre-employment screening – Individuals applying for positions with access to classified data, including new CIA, NSA, and FBI employees, are routinely polygraphed. Questions aim to uncover espionage, terrorism ties, and vulnerabilities like drug use or financial problems.
• Criminal investigations – Polygraphs are used in law enforcement to test the veracity of witnesses and suspects. Questions focus on knowledge of or participation in the crime. Examinations in espionage cases explore contacts with foreign governments and nondisclosure of classified information.
• Counterintelligence scope polygraphs – Agencies periodically re-test employees in sensitive positions to identify potential insider threats. Known as CI-Scope polygraph exams, the wide-ranging questions cover unauthorized disclosures, relationships with foreign nationals, and compliance with rules on classified data.
• Overseas operations – lie detector test vet foreign sources and collaborators working with U.S. personnel abroad. CIA officers undergo testing while deployed to identify possible unauthorized disclosures or other issues.

Types of questions asked

While exam specifics vary by purpose, polygraphs in national security contexts commonly explore:

• Unauthorized disclosure of classified information
• Foreign intelligence contacts
• Involvement in terrorism or espionage
• Falsification of background information
• Mishandling of classified data
• Drug use or other rule violations