Wis. Stat. § 609.05: Primary provider and referrals.

(1) Except as provided in subs. (2) and (3), a limited service health organization, preferred provider plan, or defined network plan shall permit its enrollees to choose freely among participating providers.

(2) Subject to s. 609.22 (4) and (4m), a limited service health organization, preferred provider plan, or defined network plan may require an enrollee to designate a primary provider and to obtain health care services from the primary provider when reasonably possible.

(3) Except as provided in ss. 609.22 (4m), 609.65, and 609.655, a limited service health organization, preferred provider plan, or defined network plan may require an enrollee to obtain a referral from the primary provider designated under sub. (2) to another participating provider prior to obtaining health care services from that participating provider.