Short answer. Yes. Rule 21, Section 1 defines a subpoena broadly enough to reach more than trial testimony: it can compel a person to attend and testify at a hearing or trial, at any investigation conducted by competent authority, or for the taking of a deposition, so an investigating body can use the same process a court would.
What the law says
Subpoena is a process directed to a person requiring him or her to attend and to testify at the hearing or the trial of an action, or at any investigation conducted by competent authority, or for the taking of his or her deposition.
Rule 21, Section 1 — Subpoena and subpoena duces tecum. Read the full provision →
What the law says
It may also require him to bring with him or her any books, documents, or other things under his or her control, in which case it is called a subpoena duces tecum.
Rule 21, Section 1 — Subpoena and subpoena duces tecum. Read the full provision →
The settings a subpoena can reach
Section 1 does not confine a subpoena to courtroom testimony. It defines it as a process requiring a person to attend and to testify at the hearing or the trial of an action, or at any investigation conducted by competent authority, or for the taking of his or her deposition. That single definition covers four distinct settings — a hearing, a trial, an investigation, and a deposition — so being told you are subpoenaed does not by itself tell you which of these you are actually being called to.
Why 'investigation' is treated the same as a trial appearance
The rule places any investigation conducted by competent authority in the very same sentence as hearings and trials, without setting a separate or lesser standard for it. That phrasing is what makes an investigative subpoena binding in the same way a trial subpoena is — the recipient is required to attend and testify, and the process carries the same basic character regardless of whether the body conducting it is a court or another competent authority.
Depositions are covered too
The same section also reaches the taking of his or her deposition — testimony given outside a courtroom, typically before trial, to preserve evidence or narrow the issues in dispute. A subpoena compelling someone to appear for a deposition works on the same basic footing as one compelling appearance at a hearing or trial, which is why a subpoena you receive may direct you to a deposition setting rather than an actual courtroom.
The added feature when documents are involved
Whatever the setting, the same process can carry one further requirement: it may also require him to bring with him or her any books, documents, or other things under his or her control, in which case it is called a subpoena duces tecum. That added feature attaches to any of the four settings above — a subpoena to an investigation, for instance, can equally be issued as a subpoena duces tecum if the investigating authority also needs specific records produced.