“...I’m going before the Steward soon...”
Carrying out justice on his land was an important part of a lord’s duty. The local courts sat monthly to hear most cases. Anything to do with church property or clergy was settled in an Ecclesiastical Court.
“...I have done my share of robbing...”
Banditry was an inevitable part of medieval life, with gangs attacking travellers on remote roads. When the kingdom was in poor condition, from war, poor harvest or weak government, banditry could increase to epidemic levels.
“...Not that it matters why you’re being hanged...”
Not every crime in medieval England was punishable by death. Our bandit has probably been found guilty before of similar offences, and been given lesser punishments. After a number of convictions, the Court might well lose patience.