Abjure the realm
There were few legal recourses open to a medieval person accused of a crime. One recourse was to claim sanctuary at specified 'safe' places, usually a church. But when an accused criminal left the relative - and temporary - safety of sanctuary he had two choices. He could become an outlaw, like the quasi-mythical figure of Robin Hood. The alternative was to swear to abjure the realm, or leave Britain forever.
The accused criminal had to officially confess his crime, and swear to leave the realm (usually within a set period of time) and never return. There was one way to legally return after abjuring the realm, and that was to get a royal pardon, though only rich or influential people could really hope to gain a pardon from the monarch.
Time period(s): Medieval