JM 9-13.510
Every nation enacts laws to protect its sovereignty and can react adversely to American law enforcement efforts to gather evidence within its borders without authorization. Such efforts can constitute a violation of that nation’s sovereignty or criminal law. You should contact the Office of International Affairs, Criminal Division, as soon as you become aware that you may need evidence located in another country to determine methods for securing assistance from abroad and to select an appropriate one.
[updated June 2018]