The subpoena is the workhorse of the data request world. It is the instrument a company receives most often, it carries the lowest legal threshold of the compulsory processes, and it is the one most likely to arrive in volume.
What a subpoena is
A subpoena is an order to produce. Two forms matter here:
- A subpoena duces tecum compels the production of documents, records, or data. This is the form companies receive.
- A testimonial subpoena compels a person to appear and give evidence.
The defining characteristic is that a subpoena can generally be issued without a judge approving it first. A prosecutor acting through a grand jury, or an agency acting under statutory authority, can issue one directly. That absence of prior judicial review is the reason its reach is limited.
What data a subpoena can reach
In the United States the boundary is drawn by the Stored Communications Act, which sorts data into tiers and assigns a different legal instrument to each.
| Subpoena | Search warrant | |
|---|---|---|
| Legal standard | Relevance to an investigation | Probable cause |
| Prior judicial approval | Not generally required | Required |
| Typical data reached | Basic subscriber information, non-content records | Content of communications, stored files |
| Who issues it | Prosecutor, grand jury, or agency | Judge or magistrate |
| Can the user be notified | Often yes, unless separately restricted | Often restricted by an accompanying order |
The practical rule of thumb is that a subpoena reaches information about an account and a warrant reaches what is inside it. The boundary is contested at the edges, and location data has been the most heavily litigated of those edges.
What it means for a company receiving one
A subpoena is compulsory, so it cannot simply be declined, but it is not self-executing either. The recipient has a genuine role: confirming the subpoena is valid and properly served, confirming the issuing authority has jurisdiction, and confirming the scope actually matches what the law permits that instrument to reach.
Three failure modes recur:
- Over-production. Answering a subpoena with content because the request asked for it, when the instrument does not reach content.
- Under-scrutiny of scope. Producing records for a date range far broader than the request justifies.
- Missing the deadline. Compliance dates are real, and an unanswered subpoena escalates.
How subpoenas differ from other legal process
A subpoena sits at the bottom of a ladder. A court order under 18 U.S.C. § 2703(d) sits above it, requiring specific and articulable facts and reaching more detailed transactional records. A search warrant sits above that, requiring probable cause and reaching content. Emergency disclosure requests sit outside the ladder entirely: they are voluntary rather than compulsory, and they carry no judicial oversight at all.
Knowing which rung an instrument occupies is the whole of the intake decision. Everything downstream depends on classifying it correctly.