Home Blog Subpoena Ad Testificandum (Legal Definition: All You Need To Know)

Subpoena Ad Testificandum (Legal Definition: All You Need To Know)

What is Subpoena Ad Testificandum?

How do you legally define it?

What are the essential elements you should know!

Keep reading as we have gathered exactly the information that you need!

Let’s dig into our legal dictionary!

Are you ready?

Let’s get started!

What It Is

A Subpoena Ad Testificandum is a summons from the court ordering an individual to appear and orally testify at a hearing.

To better understand the Latin phrase “Subpoena Ad Testificandum”, let’s break it down into its components.

“Subpoena” is a writ ordering someone to appear in court.

“Testificandum” means to appear and testify.

When you look at the phrase as a whole, a Subpoena Ad Testificandum is a court order asking a person to testify.

Subpoenas Ad Testificandum represent the legal mechanics for compelling the attendance of a witness at a certain date, certain time, and certain place.


What is the legal definition of Subpoena Ad Testificandum?

According to USLegal, “The term Subpoena Ad Testificandum signifies a formal document that orders a named individual to appear before a duly authorized body at a fixed time to give testimony.”

For the court to exercise its power to compel someone to appear in court and testify, it must serve the witness in question with a Subpoena.

The term “Subpoena” is a generic term but it can include either a Subpoena Ad Testificandum or a Subpoena duces tecum.

A Subpoena Ad Testificandum is to order a person to appear in court and testify whereas a Subpoena duces tecum is to order a person to appear in court and deliver documents, material, or things.


The purpose of the Subpoena Ad Testificandum is to have someone testify before the judge, jury, or court.

Testificandum is the Latin term referring to “testimony” or the process of acting as a witness.

In criminal or civil lawsuits, witnesses play a crucial part in allowing the parties to establish the factual grounds required for their claim or defense.

Testimonies from fact witnesses are therefore crucial in helping a party make its case or attack the other party’s claims or assertions.


In essence, a Subpoena is a writ intended to command (or order) a person to appear before the court and testify on a particular matter.

When a person receives a “Subpoena”, they are referring to a legal document issued by the court ordering them to do something.

Typically, writes are issued by the courts, judges, or other judicial bodies having the power to compel someone under its governing rules.


“Testificandum” is a Latin term meaning “to testify”.

This means that the person receiving the Subpoena Ad Testificandum is commanded to testify.

As an example, here is what the United States Environmental Protection Agency’s Subpoena Ad Testificandum indicates: 

Subpoena ad testificandum - Testificandum command

As per this text, the person is “commanded to appear in person” at the specified time, date, and place.

The Subpoena further states:

Subpoena ad testificandum - Testify under oath

The Subpoena requires that the person testify under oath and give an “oral and truthful responses to all lawful inquiries and questions put to you”.

A witness receiving a Subpoena Testificandum will clearly understand that:

  • His or her testimony is required in person
  • When and where
  • Why
  • What will happen on the day of the testimony 


A Subpoena is a legal order issued by the court to compel someone to either testify or produce documents or evidence.

In the context of an Ad Testificandum Subpoena, a person is required to present an oral account of what he or she may know about a certain event or situation.

What happens if the person fails to respect the order of the Subpoena?

There are serious legal consequences.

The failure to respect the order issued in a Subpoena is equivalent to deliberately violating a judgment from the court or an order of a judge.

This can result in the witness being found in contempt of court and be sanctioned.

The penalties can go from fines all the way to imprisonment (even in civil cases).

As an example, in the Subpoena Ad Testificandum of the State of New Jersey, it is indicated that the failure to comply with the order can “subject you to the penalties provided by law”:

Subpoena ad testificandum - Penalties

These penalties are serious and a Subpoena should not be disregarded or considered as unimportant.

Make sure you consult with a litigation lawyer or qualified attorney to understand what’s the best course of action to take.


In the United States, just like many other jurisdictions, the form of the Subpoena is prescribed by law or by the rules of the court issuing it.

There are certain fundamental elements required for a Subpoena to produce its legal effects:

  • It must name a person to appear
  • It must indicate where the person must appear to testify
  • It must be specific as to date, time, and place
  • It must state the name of the court
  • It must indicate the name of the litigants or the parties to the proceedings 

Generally, the law will prescribe certain mandatory information or disclosures to be made to the witness advising them that this is a legal order and they must comply with it.

Should a witness fail to comply with its terms, there may be legal consequences, penalties, and sanctions.

As an example, here is an Ad Testificandum form used in the State of New Jersey in the context of civil action:

Subpoena ad testificandum - Form State of New Jersey

Subpoena Ad Testificandum And Duces Tecum

In certain cases, you may see a Subpoena called “Subpoena Ad Testificandum and Duces Tecum”.

The objective of this Subpoena is twofold:

  • Ad Testificandum: to have you testify
  • Duces tecum: to have you bring evidence, documents, or material

When the court requires that a person appear before the court authority and testify and, at the same time, bring certain evidence or “things” in their possession, one Subpoena can be sent to cover both objectives.

With regards to the order to testify, the Subpoena must be clear as to who is asked to testify, when, where, what time, and the overall purpose.

With regards to the production of documents or evidence, the Subpoena must be clear as to what is requested from the witness to bring.


So what is the legal definition of Subpoena Ad Testificandum?

Let’s look at a summary of our findings.

Subpoena Ad Testificandum Meaning

  • A Subpoena Ad Testificandum is a court order compelling an individual to appear before it and testify
  • The order will name the witness, be specific as to the date, time and place, provide details as to the litigants and the court proceedings, and include other legally mandated disclosures
  • The law or the court rules generally prescribe the Subpoena format and the “template” to be used
  • Failure to respect the order of a court in an Ad Testificandum order can result in severe civil or criminal penalties 
Contempt of court
Deposition Subpoena 
Legal witness 
Oral testimony 
Subpoena duces tecum
Civil procedures
Court procedures
Court rules
Criminal procedures 
Procedural law
Uniform Rules of Criminal Procedures

Editorial Staffhttps://lawyer.zone
Hello Nation! I'm a lawyer and passionate about law. I've practiced law in a boutique law firm, worked in a multi-national organization and as in-house counsel. I've been around the block! On this blog, I provide you with golden nuggets of information about lawyers, attorneys, the law and legal theories. Enjoy!


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