Definition
An archaic Latin term of old English law denoting a coast, sea coast, or shore — the region bordering the sea. The term appears most notably in the phrase *per costeram maris*, meaning "by the sea-shore," which carried legal significance in the context of royal prerogative, trade regulation, and the rights of coastal inhabitants.
Why It Matters in Research
Researchers encountering COSTERA or the phrase *per costeram maris* will find them almost exclusively in medieval English legal sources. The term's primary legal relevance derives from its appearance in Magna Carta (9 Hen. III, c. 23), which used the phrase to define or limit certain rights and privileges associated with sea-coast activity — a provision touching on commerce, navigation, and the liberties of coastal towns and merchants.
The term is functionally obsolete in modern legal usage and will not appear in contemporary statutes or cases. Researchers working in early English legal history, particularly in connection with Magna Carta interpretation, coastal rights, admiralty antecedents, or borough and town liberties, should be alert to it. Because the term is purely Latin-French in character and appears in no modern legal taxonomy, keyword searches in modern databases will return little. Productive research requires consulting medieval Latin legal texts, glossaries such as Spelman's *Glossarium Archaiologicum*, and early English constitutional documents directly.
For corpus researchers, COSTERA connects the broader doctrinal history of coastal and admiralty jurisdiction to its medieval English foundations. The concept of the sea-shore as a legally defined zone — separating inland from maritime jurisdiction, and demarcating royal from common rights — is one that persists structurally in later admiralty and tidal waters doctrine even after the specific term falls away.
Historical Dictionary Support
Burrill's Law Dictionary is the sole source among standard Anglo-American legal dictionaries to define this term with any fullness. Burrill traces the word from the French *costier* and Latin *costa* (a side), establishing it as designating the coastal margin — *litus; regionis pars mari finitima* (the shore; the part of the region bordering the sea). The entry cites Spelman and a Towns pleading reference alongside the Magna Carta citation, confirming the term's grounding in authoritative medieval sources rather than mere antiquarian curiosity.
Other major historical legal dictionaries — including Jacob's, Tomlin's, and Black's early editions — do not appear to carry this entry, which makes Burrill's treatment the primary reference point within the standard Law Mind shelf. Researchers should treat Burrill here as a conduit to primary medieval sources rather than as an independent authority; the value of the entry lies in its Magna Carta citation and the Spelman cross-reference, both of which open paths into the original documentary record.
Jurisdictional Note
COSTERA is a term of old English law with no modern jurisdictional application. Its legal significance is effectively confined to the interpretation of medieval English royal charters and statutes, principally Magna Carta. It has no recognized analogue in American, Scottish, or other common law jurisdictions as a term of art.