Dempster

The name for a judge or arbiter of minor disputes, from Old English dem(e)stre, a derivative of the verb demian ‘to judge or pronounce judgement’. Although this was originally a feminine form of the masculine demere, by the Middle English period the suffix -stre had lost its feminine force, and the term was used of both sexes. Also possibly derived from "Doomsayer", the word for an officer of court who pronounces doom. The surname is not common in England, where the term was early replaced by Anglo-Norman French Juge, but relatively frequent in Scotland, where until 1747 every laird of a barony could have certain offenses within his territory tried by his dempster, and on the Isle of Man, where deemsters also played an important part in the administration of justice. First found in Perthshire (Gaelic: Siorrachd Pheairt) former county in the present day Council Area of Perth and Kinross, located in central Scotland, where they held a family seat from ancient times, some say before the Norman Conquest in 1066.

Also a varient of the original Irish Dempsey

The surname itself first appears in the late 13th Century, in the form of one Andrew Dempstar.