On July 2, 2008 the Michigan Supreme Court decided the case of Miller v Allstate Insurance Company.

http://courtofappeals.mijud.net/documents/OPINIONS/FINAL/SCT/20080702_S134393_97_MillervAllstate2Apr08-op.pdf

The Court held that Allstate lacked standing to challenge the corporate status of PT Works because only the Attorney General has authority to pursue a claim that a corporation is improperly incorporated. The Court did not consider or decide whether physical therapists must organize under the Professional Service Corporation Act.

In light of the Superme Court decision, effective immediately, the Corporation Division will resume its longstanding practice of requiring only corporations that provide services in a "learned profession" to form as professional corporations, consistent with OAG, 1989-1990, No 6592, p 166 (July 10, 1989).

http://www.ag.state.mi.us/opinion/datafiles/1980s/op06592.htm