So, you’ve received a third-party subpoena. Now what? A third-party subpoena is the procedural mechanism that allows parties in litigation to obtain evidence from non-party individuals and/or entities. For federal cases, Federal Rule of Civil Procedure 45 governs this process. Rule 45 outlines specific procedures that litigants must follow to serve a subpoena seeking documents and/or testimony properly. The Rule also provides protections non-parties can use to alleviate their burden in producing responsive documents. Most states have their own rules that govern non-party discovery that often, but not always, mirror Rule 45.