In Common Law and UN convention on the intenational contract for sale of goods ( cisg ) the " mitigation rule " or " the aggrived party's duty to avert or minimize his loss " is a well known rule.

According to this rule, used as a defense by the defendant in both contractual and tortious cases, the plaintiff ( injured party ) has a duty ( obligation ) to avert or minimize his loss or its consequences when he      suffered through breach of contract or tortious act.

If the defendant succeds to prove any failure on the part of the plaintiff, he will be acquitted from liability for avoidable losses. If the plaintiff takes the reasonable steps, he will be entitled to any reasonable expenses spent, when succeeding to mitigate.

The rule is accepted in Iranian laws in torts : islamic punishment code has applied it in some articles and it can be traced in other specific laws.

The most important text among the Iranian laws by which the mitigation rule has been codified, is the insurance code, but in contractual   responsibility cases this rule could not be applied, because the general sanction for breach of contract in both islamic and Iranian law is specific performance, by which the innocent party is entitled to insist on existence 

of contract and enforcement of contractual obligations.

This is the difference between Iranian law and common law. In common law this sanction is a secondary remedy and is applied with the discretion of the court. In common law the first sanction for breach of contract is recovering damages.

I have tried throughout my thesis to elaborate on the idea that the most appropriate basis for the mitigation rule is causation between the plaintiff's failure to take reasonable steps and avoidable losses.