External effects or opposabilité is a legal subject that some legal authors of France take advantage of which for clarifying the scope of the doctrine of the privity of contract and as a complementary principal. The use of the foresaid term does not go back to a long way and there is still a dispute over its bases. Because the doctrine of the privity of contract is adapted from the Civil Code of France and entered into the Civil Code of Iran, the clarification of its concepts and bases not only will be helpful in clarifying the doctrine of the privity of contract but also shows the effects of contract on third parties. For this reason, in this essay I shall try to process the concept of External Effects or Opposabilité and analyze its bases in the Iranian and French law.
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