This article aims to present the perception of the institution of a personal source of evidence such as a crown witness through the eyes of officers of the Federal Bureau of Investigation who have had contact with this very controversial institution for many years. The publication will present an anonymous survey which was conducted with FBI officers, and which aimed to answer the fundamental question, namely, whether the institution of a crown witness in the United States brings the expected benefits to the administration of justice. In addition, the survey attempted to obtain answers regarding the reasons why crown witnesses cooperate within the United States and the correctness of the use of this institution. The answers obtained were compared with identical surveys conducted in Poland by the author of this publication in 2019-2020. It should be noted that the surveys conducted are
the first of their kind which were conducted by a Polish researcher with the participation of FBI officers. In addition, the publication uses comparative material as a result of extensive research conducted by the author in 2013‒2020, which is described in detail in the item: “The institution of a crown witness in material legal, criminal procedural and empirical terms.