Violent thugs and bandits - "mercenaries - who hired out their services during the reign of Edward I; later, the ordinances issued to control them. The first commissions of trailbaston were instituted by Edward I in 1304, a time of public disorder. They were intended to deal not only with outlaws but also those who supported them and benefited from their crimes. There is an outlaw's song dating to c. 1305 in which the need to bribe sheriffs is lamented. [< trail + baston = a club, thus a person who trails a club; as we say someone's 'knuckles scrape the ground'.] -
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.