<p>Marion, Little John, Robin, Sheriff; based solely on morality and honesty.</p>
<p>Marion wished to save Robin, but assumed that the end justified the means. That doesn’t always work, but in this case, is acceptable.
Little John’s crime was to take advantage of the situation, seducing Marion at the expense of his friendship with Robin (assuming). The lesser of three evils.
Robin acted jealously, egocentrically, ungratefully, and unreasonably. He did, however, have a reason to be angry, which makes his behavior understandable.
The Sheriff took advantage of his position. He not only took advantage of Marion, but also failed in his duties as a jailkeeper. While he kept his promise, it was based on immoral grounds.</p>