null and void
adj. invalid, cancelled, unenforceable
an absolute nullity—void ab initio
In law, void means of no legal effect. An action, document, or transaction which is void is of no legal effect whatsoever: an absolute nullity — the law treats it as if it had never existed or happened. The term void ab initio, which means "to be treated as invalid from the outset," comes from adding the Latin phrase ab initio as a qualifier. For example, in many jurisdictions where a person signs a contract under duress, that contract is treated as being void ab initio.