Rechtshilfeersuchen - letter rogatory
http://www.proz.com/kudoz/german_to_english/law_general/8978...

Summary: Letters rogatory are the customary method of obtaining judicial assistance from abroad in the absence of a treaty or executive agreement. Letters rogatory are requests from courts in one country to the judiciary of a foreign country requesting the performance of an act which, if done without the sanction of the foreign court, could constitute a violation of that country's sovereignty. Letters rogatory may be used in countries where multi-lateral or bilateral treaties on judicial assistance are not in force to effect service of process or to obtain evidence if permitted by the laws of the foreign country. 22 CFR 92.54 provides a definition of letters rogatory.

http://travel.state.gov/law/info/judicial/judicial_683.html

The Court next considers the Convention on Mutual Assistance in Criminal Matters of 27 September 1986 between the Parties. Djibouti claimed in the first place that Article 1 of the Convention places France under an obligation to execute the international letter rogatory.

http://www.icj-cij.org/docket/files/136/14570.pdf