How is responsibility determined when the victim and the executioner disagree on the intent behind offering the left hand?

Primary text

If the victim claims he offered the left hand as a substitute for the right, while the claimant alleges it was offered without compensation or due to confusion ('desha), the statement of the victim (the one offering the hand) is accepted, as he knows his own intention best, and it is unlikely one would offer a limb for cutting gratuitously when retribution is already due.