No process, requirement of a report, inspection, or other investigative act or demand shall be issued, made, or enforced in any manner or for any purpose except as authorized by law.
Whenever an agency or person is authorized or required to give any notice under this chapter, unless a different method of giving such notice is otherwise expressly permitted or prescribed, such notice shall be given either by personal delivery thereof to the agency or person to be so notified, or by depositing such notice in the United States mail, postage prepaid, in an envelope addressed to such agency or person at the last-known address of such agency or person. Proof of the giving of notice in either such manner may be made by the affidavit of any officer or assistant or employee of the agency, or by affidavit of any person over eighteen years of age, naming the agency or person to which or to whom such notice was given and specifying the time, place and manner of the giving thereof.
All acts or parts of acts which are inconsistent with the provisions of this chapter are hereby repealed to the extent of such inconsistency, but such repeal shall not affect pending proceedings. No subsequent legislation shall be held to supersede or modify the provisions of this chapter except to the extent that such legislation shall do so specifically and expressly.
Nothing in this chapter shall be held to limit or repeal additional requirements imposed by statute or otherwise recognized by law. No procedural requirement shall be mandatory as to any agency proceeding initiated prior to the effective date of this chapter. If any provision of this chapter or the application thereof to any person or circumstance is held invalid, such invalidity shall not affect other provisions or applications of the chapter which can be given effect without the invalid provision or its application, and to this end the provisions of this chapter are declared to be severable.