letters rogatory
Concise Oxford English Dictionary © 2008 Oxford University Press:
letters rogatory /ˈrəʊgət(ə)ri/
▶plural noun Law documents making a request through a foreign court to obtain information or evidence from a specified person within the jurisdiction of that court.
– origin C19: rogatory from med. L. rogatorius ‘interrogatory’.
'letters rogatory' also found in these Oxford entries:

