For Case Development on Foreign Evidence issues, see her blog Obtaining Foreign Evidence
Treatises:
Obtaining Evidence Abroad in Criminal Cases, Michael Abbell, Transnational Publishers ISBN 1-57105-215-1.
Also, see CHAPTER 6 on Foreign Evidence Issues, Cultural Issues in Criminal Defense, 2d. Ed. 2007 JurisPub.com

FEDERAL LAW ISSUES IN OBTAINING EVIDENCE ABROAD Linda Friedman Ramirez
GLOSSARY Mutual Legal Assistance Treaties, or MLAT's
(A list of Bilateral Mutual Legal Assistance Treaties can be found at the Department of State webpage.
"Traditionally, evidence sought by a foreign government had to be obtained through a process whereby a written request known as a "letter rogatory" was sent from the court of one country to the court of another asking the receiving court to provide the assistance. A federal statute authorizes federal district courts in this country to entertain such requests and provides that "[t]he district court of the district in which a person resides or is found may order him to give his testimony or statement or to produce a document or other thing for use in a proceeding in a foreign or international tribunal, including criminal investigations conducted before formal accusation." 28 USC 1782 Not only can a foreign tribunal bring a request in the form of a "letter rogatory," but section 1782 has been amended to also allow similar requests for assistance to be brought by "interested persons" including foreign governments in foreign investigations or proceedings and private litigants of a foreign proceeding. Requests for assistance initiated directly by an interested person rather than a foreign court are often referred to as "letters of request." Despite the apparent versatility of 28 USC 1782 law enforcement authorities found the statute to be an unattractive option in practice because it provided wide discretion in the district court to refuse the request and did not obligate other nations to return the favor that it grants. MLATs, on the other hand, have the desired quality of compulsion as they contractually obligate the two countries to provide to each other evidence and other forms of assistance needed in criminal cases while streamlining and enhancing the effectiveness of the process for obtaining needed evidence. This MLAT between the United States and Canada provides for a broad range of cooperation in criminal matters. "
"In re Commissioner's Subpoenas" 325 F.3d 1287, (11th cir. 2003).
Do MLAT's provide an opportunity for Defendants to obtain evidence abroad?
Article 2 of the Inter-American Convention on Mutual Assistance in Criminal Matters states: "This convention applies solely to the provision of mutual assistance among states parties. Its provisions shall not create any right on the part of any private person to obtain or exclude any evidence or to impede execution of any request for assistance."