Subpoena
A court-issued legal order compelling a person to testify at a deposition or trial, or to produce documents — failure to comply is punishable as contempt of court.
A subpoena is a court-issued order requiring a person to appear and testify (subpoena ad testificandum) or to produce documents, records, or other evidence (subpoena duces tecum). Attorneys can issue subpoenas in cases where they are admitted as counsel without a judge signing them, though the authority derives from the court. Subpoenas can be served on parties and non-parties alike.
Receiving a subpoena creates a legal obligation to comply. Failure to obey is contempt of court, potentially resulting in fines or jail. However, there are legitimate grounds to object: privilege (attorney-client, doctor-patient, spousal), relevance, undue burden, or procedural defects. If you believe a subpoena is improper, you must file a motion to quash or modify before the compliance deadline — ignoring it is not an option.
Third-party subpoenas — to banks, phone companies, employers, or cloud services — are common discovery tools. These entities typically require the subpoena before disclosing customer records. Many companies have designated legal compliance departments that handle subpoena responses without the account holder's knowledge unless notice is legally required.
Real-World Example
The plaintiff's attorney subpoenaed the defendant's cell carrier for location records from the night of the accident; the carrier complied after receiving the subpoena and court order, producing data placing the defendant at the scene.