Cabinet noir

In France, the cabinet noir (French for "black room", also known as the "dark chamber" or "black chamber") was a government intelligence-gathering office, usually within a postal service, where correspondence between persons or entities was opened and read by government officials before being forwarded to its destination.^[1] However, this had to be done with some sophistication, as it was considered undesirable if the subjects of the practice knew about it, and important "that the black chamber not interrupt the smooth running of the postal service."^[2] This practice had been in vogue since the establishment of postal and telegraphy services, and was frequently used by the ministers of Louis XIII and Louis XIV; but it was not until the reign of Louis XV that a separate office for this purpose was created. This was called the cabinet du secret des postes, or more popularly the cabinet noir. Although declaimed against at the time of the French Revolution, it was used both by the revolutionary leaders and by Napoleon.^[3][4]