The doctrines of good faith and fair dealing, fiduciary duty, and unjust enrichment are doctrines of last resort because they are activated only when all other potentially applicable commands from constitutions, statutes, regulations, ordinances, common law decisions and contracts have been exhausted. In these circumstances ⎯ where positive law and private ordering are otherwise incomplete ⎯ contracting parties rely heavily on informal social sanctions to protect against opportunism, but the doctrines of last resort reinforce these social sanctions. Rather than regulating all of the deviations and adjustments that are common in contractual relationships, doctrines of last resort constrain extreme deviations from social norms, reinforcing agreements precisely in those contexts where informal social sanctions are weakest.