Rule 1566 This article applies in any proceeding in which testimony can be compelled.

If a court or other legal proceeding has the power to force someone to testify, the rules in this article apply. This covers more than just trials. It includes hearings, depositions, grand jury proceedings, and other legal settings where attendance and testimony can be required by law.

The key factor is whether testimony can be compelled, meaning someone can be legally ordered to show up and answer questions. If that power exists in the proceeding, these rules are in play.