A subpoena is a legal document issued by the Court at the request of a party to a case. A subpoena compels a person to produce documents or give evidence at a hearing or trial.
In NSW, it is a criminal offence to ignore a subpoena. If you have been served with one, you will be required to attend court or submit the documentary evidence listed on the subpoena.
You can listen to the story regarding this issue on SBS Korean.