Void means without legal effect. Ab initio is a Latin term meaning “from the beginning”. Void ab initio, therefore, means an action that never had legal effect. A void act cannot be rectified to become enforceable because it is deemed as though it never occurred, and the parties are placed in their original positions.
In terms of legislation, for example, a statute enacted in excess of power or an unconstitutional provision of an act are void ab initio, that is, they are inoperative as if they had never been passed.
In the context of contract law, a contract may be “void ab initio”. This means that the contract must be treated as invalid from the moment that it was entered into, rather than when the court made a decision on the matter. The effect of a contract being void ab initio is that the contract has no binding power over any of the parties.
A circumstance that may render a contract void ab initio is when a contract is invalid due to common mistake of a material fact or for duress.