Marion, did her best in the circumstances, I'd throw Robin to the lions!

Marion did make a difficult choice for reasons that seemed best to her. The issue of whether the Sheriff had done anything wrong in arresting a known thief and his accomplices seems relevant here. Robin would have had no right to criticise Marion's flexible ethics, given that he justified actions that were illegal, and no doubt considered immoral by some, on the basis of "the greater good." Where does one draw the line? I have heard that good intentions can make dangerous paving stones.