What is the purpose of a "subpoena"?

A subpoena serves the critical function of compelling an individual to either appear in court as a witness or to provide specific evidence relevant to a legal proceeding. This legal tool is essential for the gathering of evidence and ensuring that witnesses fulfill their obligations to testify or supply documents. By issuing a subpoena, the legal system can enforce attendance and the production of necessary materials, which contributes to a fair and just judicial process.

The other options focus on different legal processes and documents. While legal representation is important in court, it is not the function of a subpoena. Similarly, certifying legal authority is the role of documents like powers of attorney or official court orders, not a subpoena. Lastly, a notice of a court hearing informs parties of when and where a case will be heard but does not compel attendance or production of evidence in the same way a subpoena does.