In subject literature devoted to police formations in various countries, we can find a lot of terms describing essentially the same institution concerning the police officer’s secret actions — “undercover”, the so called “police agent”. In the legal and penal order of many countries the terminology concerning the police agent’s institution has not been standardized until now, no single term covering this issue has been elaborated so far. The most frequent terms that may be encountered are: “secret investigative agent“, “secret police officer“, “undercover agent“, “covert“ or “secret agent“. Not only are we dealing with a situation in which
in practice there is no one international and universal term describing this issue, but also in majority of European countries there are various determinants and criteria enabling the practical use of this “tool, designated for the fight against criminality. The factors that affect it include, for example: the implications provided to law enforcement authorities by domestic and international activities of organized crimes which, in turn, forces us to identify and define emerging threats and to modify and adjust practical actions concerning the police, prosecutor’s office and courts in their fight with this specific kind of criminal activity. For this reason, we may be able to find various doctrines concerning the procedure of using the institution of the police agent’ in the fight against criminality all over the world. The article has been prepared as part of theresearch project called “Understand the Dimensions of Organized Crime and Terrorist Networks for Developing Effective and Efficient Security Solutions for First-line-practitioners and Professionals” (Project: TAKEDOWN, H2020-FCT-2015, No.: 700688).