What is a subpoena?

A subpoena is indeed a legal document issued by a court or other authorized entity that commands an individual to appear in court as a witness or to produce specified documents or evidence. It plays a crucial role in legal proceedings, ensuring that relevant information and testimony can be acquired to support a case.

In the context of the choices provided, this definition aligns perfectly with the correct answer. Subpoenas serve as an essential mechanism for enforcing legal compliance during investigations and trials, thereby helping to establish the truth and uphold justice.

Understanding the function and significance of a subpoena is vital for professionals in psychology and related fields, especially when dealing with cases that may involve court appearances or the necessity to provide confidential information under legal obligation.