What trips people up most is that a subpoena is not just a request. It is a formal court-backed order requiring a person, business, or other nonparty to do something specific - usually appear to testify, produce documents, or both. A subpoena can be directed to a witness for a deposition, to someone for trial testimony, or to a hospital, employer, phone carrier, or other record holder for evidence. Ignoring one can lead to court enforcement and possible penalties unless it is challenged or modified.

In practice, subpoenas are how parties get information they do not already have. In an injury case, that may include medical records, wage records, surveillance footage, maintenance logs, or testimony from a treating provider or eyewitness. For someone hurt in a crash, on a job site, or in a tunnel backup after heavy rain in Boston, a subpoena may help prove how the incident happened and how serious the injuries are.

In Massachusetts, subpoenas in civil cases are governed mainly by Massachusetts Rule of Civil Procedure 45. That rule sets out how subpoenas are issued, served, objected to, and sometimes quashed. A subpoena can affect an injury claim by uncovering helpful evidence, but it can also raise privacy and burden issues, especially when the other side seeks broad medical or employment records.