De facto doctrine preserves validity of acts by persons exercising office under colourable authority, protecting public reliance and order. The de facto doctrine treats acts of persons exercising public office under colourable authority or public acquiescence as valid for the protection of the public and third parties, distinguishing de facto officers from intruders; such acts remain effective while the person occupies the office unless the officer's title is directly challenged and determined in a regular proceeding or when the person seeks private rights by virtue of the contested office.