A kind of commission from a judge authorizing and requesting a judge of another jurisdiction to examine a witness. A letter rogatory is an instrument sent in the name and by the authority of a judge or court to another, requesting the latter to cause to be examined, upon interrogatories filed in a cause depending before the former, a witness who is within the jurisdiction of the judge or court to whom such letters are addressed. In letters rogatory there is always an offer on the part of the court whence they issued, to render a similar service to the court to which they may be directed whenever required.