early 15c., "sale of ecclesiastical or state offices," from Old French baraterie "deceit, guile, trickery," from barat "malpractice, fraud, deceit, trickery," which is of unknown origin, perhaps from Celtic. In marine law, "wrongful conduct by a ship's crew or officer, resulting in loss to owners," from 1620s.
Meaning "offense of habitually starting legal suits" is from 1640s. The sense has been somewhat confused with that of Middle English baratri "combat, fighting" (c. 1400), from Old Norse baratta "fight, contest strife." This was an active word in Middle English, with forms such as baraten "to disturb the peace" (mid-15c.); baratour "inciter to riot, bully" (late 14c., mid-13c. as a surname).
Barataria Bay, Louisiana, U.S., is from Spanish baratear "to cheat, deceive," cognate of the French word; the bay so called in reference to the difficulty of its entry passages.