explains the elements necessary to form a legally enforceable contract, selecting one or two of those hints below on contract law

Hints on Contract Law.

promise, bargained, consideration, "offer" that creates the power of acceptance, mutual assent, writing signed by the party to be charged, "statute of frauds, free from fatal defects (the absence, illegality), "unjust enrichment", "quasi-contract"

What is the responsibility of each party in determining these elements and when (if ever) would governmental intervention become necessary to balance the interests of the parties rather than simply enforcing the deal they have reached?