Baron Corbin has been appointed by Stephanie McMahon to assist Kurt Angle.
During Raw, Curt Hawkins' attempt to break his 199 match losing streak was thwarted by Baron Corbin. Hawkins was disqualified because Corbin attacked his opponent and Hawkins moved onto 200 straight losses. Afterwards, Corbin went to Kurt Angle to let him know that Stephanie McMahon has made him Constable of Raw.
Since the introduction of Ronda Rousey, Angle has been antagonized by Stephanie McMahon and Triple H because he revealed their ulterior motives towards Rousey. Constable Corbin seems to be part of Stephanie McMahon's continued needling of Angle.
A Constable is usually a law enforcement member and can range from a particular rank of police officer to an elected official. Corbin was made a Constable as a way for Stephanie McMahon to keep eyes on the decision making of Kurt Angle.