Keeper of the Code was the title given to a specially appointed member of the Brethren Court. It was the responsibility of the Keeper to ensure the Pirata Codex was followed to the letter by the Pirate Lords.
As of the fourth meeting of the Brethren Court, Captain Edward Teague was the Keeper of the Code, and was not above killing anyone who dared suggest the Court should overlook the Code—as he demonstrated by shooting Askay for asking the pirates to "hang the Code". The keys to the Pirata Codex were kept by the Prison Dog in Shipwreck City, and the Code itself was carried to meetings by two wizened aides.
When one does become keeper of the Code he or she is ineligible to be voted or have a vote in who is to become the Pirate King.