From the beginning. An agreement is said to be "void ab initio" if it has at no time had any legal validity. A party can be a trespasser, an agreement or deed can be void, or a marriage or can be unlawful, ab initio. The illegality of the conduct or can make the entire situation illegal ab initio (from the beginning), not just from the time the wrongful behavior occurs. If a sheriff enters property under the authority of a court order requiring him to seize a valuable painting, but instead he takes an expensive marble sculpture, he would be a trespasser from the beginning. Since the officer abused his authority, a court would presume that he intended from the outset to use that authority as a cloak from under which to enter the property for a wrongful purpose. This theory, used to correct abuses by public officers, is not popular now a days. The Courts have held that the seizure in an illegal search need not be illegal.

++ A show-cause notice and demand contrary to existing circulars of the Board are ab initio bad.

++ the impugned order not being found to be void ab initio, no further curative steps may be taken

++ Electricity under the Central Excise Act, 1944 read with Central Excise Tariff Act, 1985 is not excisable goods. The proposal to bring in the provisions of Rule 6 of Cenvat Credit, 2002 cannot be upheld ab initio as that rule is applicable only to goods which are excisable and further exempt or at Nil rate of duty.