Parliamentary scrutiny of delegated rules requires laying rules before Parliament and allows modification or annulment affecting future effect. Every rule made by the Central Government under the Act must be laid before each House of Parliament for a total period of thirty days, which may span one or more sessions. If, before the expiry of the session immediately following that period, both Houses agree to modify or to annul the rule, the rule will thereafter operate only in the modified form or be of no effect; such modification or annulment does not affect the validity of anything previously done under the rule.