The “de factor officer” doctrine:
The de facto officer doctrine confers validity upon acts performed by a person acting under the color of official title even though it is later discovered that the legality of that persons appointment or election to office is deficient. Norton v. Shelby County, 118 U.S. 425, 440, 6 S.Ct. 1121, 1124, 30 L.Ed. 178 (1886).
The de facto doctrine springs from the fear of the chaos that would result from multiple and repetitious suits challenging every action taken by every official whose claim to office could be open to question, and seeks to protect the public by insuring the orderly functioning of the government despite technical defects in title to office. 63A Am.Jur.2d, Public Officers and Employees § 578, pp. 1080-1081 (1984)
http://www.lasc.org/opinions/2001/00ka2864.opn.pdf
Simarly cited here (& elsewhere): "State of Vermont v Wanita Oren" http://info.libraries.vermont.gov/SUPCT/160/op92-113.txt