Contracts for illegal purposes are not enforceable at law.However, a movement in the 1990s to replace the separate teaching of contract and tort with a unified law of "obligations" has met with little success.An innocent party wishing to set aside a contract for duress to the person need only to prove that the threat was made and that it was a reason for entry into the contract; the burden of proof then shifts to the other party.

 Otherwise, the parties may enter into a binding agreement without signing a formal written document.121 Choice of forum edit Many contracts contain a forum selection clause setting out where disputes in relation to the contract should be litigated.Pacta conventa quae neque contra leges, neque dolo malo inita sunt, omni modo observanda sunt.

In some cases, courts look at these adhesion contracts with a special scrutiny due to the possibility of unequal bargaining power, unfairness, and unconscionability.The requirements for a contract in Anglo-American law are that there be an offer, an acceptance, consideration and an intention to effect legal obligations.