Definition
Latin. "Upon the high sea." A jurisdictional and descriptive term used in admiralty and common law pleading to designate conduct, offenses, or transactions occurring on the open ocean — that is, beyond the territorial waters subject to any particular sovereign's ordinary jurisdiction. The phrase appears most frequently in the context of maritime crimes (particularly piracy and felonies committed at sea), admiralty jurisdiction, and the conflict between common law courts and admiralty courts over subject-matter authority.
Why It Matters in Research
This term is primarily a term of art in historical admiralty pleading and jurisdictional writing rather than a term of substantive doctrine. Researchers encountering it in early common law and admiralty sources should understand it as a locational marker with significant jurisdictional consequences: conduct alleged to have occurred super altum mare was, at common law, generally triable only in admiralty or under special statutory commissions (such as those created by the early Tudor piracy statutes), not in the ordinary common law courts. The phrase thus sits at the center of the centuries-long rivalry between the Court of Admiralty and the common law courts, with figures like Coke aggressively limiting admiralty jurisdiction over matters alleged to have occurred on the high seas.
When researching crimes at sea — piracy especially — note that whether conduct occurred super altum mare versus within the body of a county (infra corpus comitatus) was often the dispositive jurisdictional question. Cases and pleadings will turn on this distinction. Researchers working in Holt-era and earlier English materials will find the phrase used with technical precision in this jurisdictional battle.
Historical sources cite Hobart 212 and 2 Lord Raymond 1453 for this phrase; Burrill adds Molloy's De Jure Maritimo and Kent's Commentaries, pointing researchers toward the two major treatise traditions — the English maritime law tradition (Molloy) and its American reception (Kent). These are productive next steps in any research trail involving this phrase.
The phrase does not appear with frequency in modern legal writing, having been absorbed into the modern concept of the "high seas" as used in admiralty jurisdiction statutes and international law. Researchers working in contemporary materials should translate the concept to the modern statutory and treaty framework governing the high seas.
Historical Dictionary Support
Black's, Rapalje & Lawrence, and Burrill are in complete agreement on the core definition — "on the high sea" or "upon the high sea" — and all three cite Hobart 212 and 2 Lord Raymond 1453. Burrill's entry is the most useful for researchers because it adds Molloy's De Jure Maritimo et Navali and Kent's Commentaries, situating the phrase within the broader treatise literature on maritime law. Neither Black's nor Rapalje & Lawrence does this.
Both Black's and Rapalje & Lawrence embed the maxim Super fidem chartarum, mortuis testibus, erit ad patriam de necessitate recurrendum immediately following the super altum mare entry — a sequential artifact of Latin alphabetization, not a substantive connection. Researchers should note that this maxim (concerning proof of charters by jury when witnesses are dead) is entirely unrelated to the high seas phrase.
None of the three historical dictionaries provides substantive analysis of the jurisdictional conflict that makes the phrase significant. They record the definition and citations, but the interpretive weight must be supplied by the treatise sources they point to.
Jurisdictional Note
As a term of historical English admiralty pleading, super altum mare does not vary across American jurisdictions in any meaningful modern sense. In American law, the concept has been translated into federal admiralty jurisdiction over matters arising on the "high seas," governed by federal statute and international treaty rather than by common law pleading formulas.