dedimus potestatum

Definition from Nolo’s Plain-English Law Dictionary

An outdated legal procedure that permitted a party to take and record the testimony of a witness before trial, but only when that testimony might otherwise be lost. For example, a party to a lawsuit might use the procedure to obtain the testimony of a witness who was terminally ill and might not be able to testify at the trial. Nowadays, the Federal Rules of Civil Procedure routinely permit the taking of testimony before trial if that testimony might otherwise be lost.

Definition provided by Nolo’s Plain-English Law Dictionary.