An unenforceable contract is one which is valid in itself, but is not capable of being enforced in a court of law because of some technical defect such as absence of writing, registration, requisite stamp, etc., or time barred by the law of limitation. For example, an oral arbitration agreement is unenforceable because the law requires an arbitration agreement to be in writing. Similarly, a bill of exchange or promissory note, though valid in itself, becomes unenforceable after three years from the date the bill or note falls due, being time barred under the limitation act.