From the Document: "Although the crimes may be many, so are the obstacles to their enforcement. For both practical and diplomatic reasons, criminal investigations within another country require the acquiescence, consent, or preferably the assistance, of the authorities of the host country. The United States has mutual legal assistance treaties with several countries designed to formalize such cooperative law enforcement assistance. Searches and interrogations carried out on our behalf by foreign officials, certainly if they involve Americans, must be conducted within the confines of the Fourth and Fifth Amendments. And the Sixth Amendment imposes limits upon the use in American criminal trials of depositions taken abroad. Our recently negotiated extradition treaties address some of the features of our earlier agreements which complicate extradition for extraterritorial offenses, i.e., dual criminality requirements and exemptions on the basis of nationality or political offenses. To further facilitate the prosecution of federal crimes with extraterritorial application Congress has enacted special venue, statute of limitations, and evidentiary statutes."
CRS Report for Congress, 94-166