Police corruption is a problem that affects societies around the world, including Europe. In recent years, several high-profile cases have been detected in countries such as Spain, Italy, France, Germany, and Greece, where officers have been removed from service for alleged links to drug trafficking, the mafia, and other criminal organizations. These events have generated deep concern among European citizens and have eroded trust in law enforcement forces.

The Polygraph as a Tool

In this context, the polygraph presents itself as a useful tool to combat police corruption. This instrument, also known as a lie detector, records a person’s physiological responses to a series of questions, such as heart rate, blood pressure, and skin conductance. These responses are considered to indicate whether a person is being honest or not.

Benefits of Using the Polygraph

The implementation of the polygraph in the fight against police corruption offers various benefits:

Deterrent effect: The knowledge by officers that they can be subjected to a polygraph test can act as a deterrent, preventing the commission of corrupt acts.

Detection of corrupt officers: The polygraph facilitates the identification of those officers who are lying about their involvement in corrupt activities.

Evidence gathering: The results of a polygraph test can be used as evidence in a judicial process, strengthening investigations and cases against those involved.

Use of the Polygraph in Police Selection

It is important to highlight that the use of the polygraph is not limited to investigating corruption cases. In many countries around the world, such as the United States, Israel, and Japan, it is used as a tool in the selection of new police officers. This way, it seeks to ensure the integrity and reliability of future members of law enforcement.

Benefits for Internal Affairs Departments

Police internal affairs departments are responsible for investigating irregularities and misconduct committed by officers. The use of the polygraph can be an invaluable tool for these units, as it allows them to:

Conduct more efficient investigations: The polygraph can help quickly determine whether an officer is hiding information or lying about their involvement in an irregular event.

Identify responsible parties: The test results can be used to identify officers who have committed misconduct or crimes, facilitating the corresponding disciplinary or legal measures.

Protect the integrity of the institution: The use of the polygraph contributes to maintaining public trust in the police, by demonstrating that measures are being taken to purge corrupt members.

Cases of Police Corruption in Europe


In Spain, police corruption has been the subject of great attention in recent years. Some relevant cases include:

Operation Nécora: dismantled a drug trafficking network involving Civil Guard officers.

Malaya Case: an urban corruption scheme in Marbella involving several local police officers.

Gürtel Case: a political corruption network that also affected some members of the security forces.


Mafia Capitale Operation: dismantled a mafia network that had infiltrated Rome’s public administration. In this case, the polygraph was used to identify police officers who were colluded with the mafia.

Ruby Case: a sexual scandal involving then-Prime Minister Silvio Berlusconi and a young Moroccan woman. Some of the police officers involved in the investigation were accused of corruption for accepting bribes.


Cahuzac Case: a tax evasion scandal involving then-Budget Minister Jérôme Cahuzac. The polygraph was used to investigate police officers who leaked confidential information about the case.

Sarkozy Case: a corruption scandal involving then-President Nicolas Sarkozy. Some of the police officers involved in the investigation were accused of corruption for accepting bribes.


Cuckoo Clock Case: a corruption scandal involving several police officers in the city of Munich. Officers were accused of accepting bribes in exchange for not fining drivers who broke the law.

GSG 9 Case: a corruption scandal involving the German police’s anti-terrorist unit. Officers were accused of embezzlement and accepting gifts from private companies.


Siemens Case: a corruption scandal involving the German company Siemens and several Greek government officials. Police officers investigating the case were accused of accepting bribes to cover up the company’s corrupt activities.

Golden Dawn Case: a corruption scandal involving the neo-Nazi political party Golden Dawn. Police officers investigating the case were accused of not acting with due diligence to prevent the party’s violent attacks.

These cases highlight the need for effective tools to combat police corruption. The polygraph, endorsed by the European Polygraph Association, presents itself as a useful tool to prevent, detect, and combat this problem, strengthening trust in law enforcement and protecting the integrity of institutions.

Creating a polygraph questionnaire specifically designed to detect corruption in police officers requires careful consideration of both ethical and legal considerations. Polygraph questionnaires must be administered by trained and certified professionals and must comply with applicable regulations and laws. Here is an example of how such a questionnaire could be structured, focused on assessing integrity and adherence to ethical principles, without assuming prior guilt. This questionnaire is purely illustrative and should be reviewed and adjusted by experts in the field according to the specific context and local regulations.

Polygraph Examination Model for Police Officers

Section 1: Informed Consent and Preparation

Have you been informed about the procedures of this polygraph test?

Do you understand that your participation in this test is voluntary?

Have you been informed of your right to consult with a lawyer before the test?

Section 2: Basic Information

Have you provided true information in your job application and all related documents?

Have you knowingly omitted relevant information that you were requested to provide to your department?

Section 3: Professional Conduct

During your service, have you witnessed acts of corruption by other officers and not reported them?

Have you ever accepted gifts, favors, or money that are not allowed by your department’s policies?

Have you used your position as a police officer to obtain illegal personal benefits?

Section 4: Financial Integrity

Have you been involved in activities that could be considered a conflict of interest with your position as a police officer?

Have you received money or goods in exchange for influencing your decisions or actions as a police officer?

Section 5: Confidentiality and Information Use

Have you shared confidential or sensitive information obtained through your work with unauthorized individuals?

Have you manipulated or altered official reports or records to cover up wrongful acts by yourself or colleagues?

Section 6: Relationships and Personal Conduct

Have you used your authority to intimidate or coerce individuals for your personal benefit or that of others?

Have you engaged in illegal activities while off duty?

Have you consumed illegal drugs while on duty?

Have you ever served under the influence of alcohol?

Section 7: Adherence to the Law

Have you knowingly ignored violations of the law by colleagues or other individuals?

It is essential to remember that questions should be formulated clearly and directly, avoiding ambiguities. Additionally, this questionnaire is only a starting point and should be adapted to the specific needs of each situation and in accordance with applicable laws. The administration of polygraph tests must always be conducted within a framework of respect for human rights and individual freedoms.


The use of the polygraph is not a magic solution, but it is a valuable tool that can be used to combat police corruption. Its implementation, along with other measures, can help strengthen public trust in law enforcement and ensure the integrity of institutions.

Additional Resources:

European Polygraph Association

National Research Council. The Polygraph and Lie Detection