Wisconsin Statutes
Wis. Stat. § 133.03 (2026)
Unlawful contracts; conspiracies
✓ current as of July 2026
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133.03(1)(1) Every contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or commerce is illegal. Every person who makes any contract or engages in any combination or conspiracy in restraint of trade or commerce is guilty of a Class H felony, except that, notwithstanding the maximum fine specified in s. 939.50 (3) (h), the person may be fined not more than $100,000 if a corporation, or, if any other person, may be fined not more than $50,000.
133.03(2)(2) Every person who monopolizes, or attempts to monopolize, or combines or conspires with any other person or persons to monopolize any part of trade or commerce is guilty of a Class H felony, except that, notwithstanding the maximum fine specified in s. 939.50 (3) (h), the person may be fined not more than $100,000 if a corporation, or, if any other person, may be fined not more than $50,000.
133.03(3)(3) As an alternative to the criminal penalties for violation of this section, the department of justice or district attorney may bring an action for a civil forfeiture. In an action for a civil forfeiture under this subsection a corporation may be required to forfeit not more than $100,000 and any other person may be required to forfeit not more than $50,000.
133.03(4)(4) This section does not apply to ambulance service contracted for under ss. 59.54 (1), 60.565, 61.64 and 62.133.
133.03 Annotation“Rule of reason” and “illegal per se” rules are discussed. Grams v. Boss, 97 Wis. 2d 332, 294 N.W.2d 473 (1980).
133.03 AnnotationOnly unreasonable restraints on trade are prohibited. Independent Milk Producers Coop. v. Stoffel, 102 Wis. 2d 1, 298 N.W.2d 102 (Ct. App. 1980).
133.03 AnnotationRefusal by a city to provide sewage service to a portion of a town unless inhabitants agreed to annexation of that portion did not violate antitrust law. Town of Hallie v. City of Chippewa Falls, 105 Wis. 2d 533, 314 N.W.2d 321 (1982).
133.03 AnnotationThe antitrust law demonstrates the legislature’s intent to subordinate city home-rule authority to its provisions. Unless legislation at least impliedly authorizes a city’s anticompetitive action, the city has violated the antitrust law. Amer. Med. Transp. v. Curtis-Universal, 154 Wis. 2d 135, 452 N.W.2d 575 (1990).
133.03 AnnotationThe test for applicability of the state antitrust law is whether the legislature intended to allow municipalities to undertake such actions. A city may tie the provision of sewage services to an area outside the city to the acceptance by the area’s inhabitants of the city’s other services. Town of Neenah Sanitary District No. 2 v. City of Neenah, 2002 WI App 155, 256 Wis. 2d 296, 647 N.W.2d 913, 01-2520.
133.03 AnnotationTo prove an allegation of predatory pricing, the plaintiff must show: 1) the prices and other direct revenues from the practice complained of are below an appropriate measure of the defendant’s costs; and 2) the defendant has a dangerous probability of recouping its investment losses in its below-cost prices by later raising prices above competitive levels. Conley Publishing Group, Ltd. v. Journal Communications, Inc. 2003 WI 119, 265 Wis. 2d 128, 665 N.W.2d 879, 01-3128.
133.03 AnnotationChapter 133, particularly s. 133.03, applies to interstate commerce in some circumstances. A complaint under ch. 133 must allege that: 1) actionable conduct, such as the formation of a combination or conspiracy, occurred within this state, even if its effects are felt primarily outside Wisconsin; or 2) the conduct complained of substantially affects the people of Wisconsin and has impacts in this state, even if the illegal activity resulting in those impacts occurred predominantly or exclusively outside this state. Olstad v. Microsoft Corporation, 2005 WI 121, 284 Wis. 2d 224, 700 N.W.2d 139, 03-1086.
133.03 AnnotationThe public interest and welfare of the people of Wisconsin are substantially affected, as required in Olstad, if prices of a product are fixed or supplies thereof are restricted as the result of an illegal combination or conspiracy. Meyers v. Bayer AG, 2006 WI App 102, 293 Wis. 2d 770, 718 N.W.2d 251, 03-2840.
133.03 AnnotationThe test for substantial effects under Olstad requires that the appellants allege: 1) specific effects on Wisconsin commerce, not merely effects that are nationwide; and 2) that these effects on Wisconsin are more than a general nationwide effect on price. Szukalski v. Crompton Corporation, 2006 WI App 195, 296 Wis. 2d 728, 726 N.W. 2d 304, 03-3132.
133.03 AnnotationWhen the circumstances involve interstate commerce and the challenged conduct occurred outside of Wisconsin, a complaint under ch. 133 is sufficient if it alleges price fixing as a result of the formation of a combination or conspiracy that substantially affected the people of Wisconsin and had impacts in this state. Plaintiffs are not required to assert allegations of disproportionate impacts on Wisconsin. An allegation that thousands of Wisconsin consumers paid supracompetitive prices as a result of monopolistic conduct by an interstate seller states a basis for recovery. Meyers v. Bayer AG, 2007 WI 99, 303 Wis. 2d 295, 735 N.W.2d 448, 03-2840.
133.03 AnnotationChapter 125 contemplates and expressly directs that regulation is to supersede competition in the retail sale of alcohol beverages. The regulatory scheme indicates a legislative intent to make state antitrust law not applicable by authorizing contrary or inconsistent conduct by granting municipalities broad statutory authority to prescribe or orchestrate anticompetitive regulation in the sale and consumption of alcohol if that regulation serves an important public interest. Private parties are eligible for antitrust immunity when they act in concert, in an anticompetitive manner, in direct response to pressure bordering on compulsion from a municipality. Eichenseer v. Madison-Dane County Tavern League, Inc. 2008 WI 38, 308 Wis. 2d 684, 748 N.W.2d 154, 05-1063.
133.03 AnnotationThe state antitrust statute was intended to be a reenactment of the federal Sherman Antitrust Act and is generally controlled by federal court decisions. Lerma v. Univision Communications, Inc. 52 F. Supp. 2d 1011 (1999).
Notes of Decisions
Cited in 64
cases (4 in the last 5 years), 1982–2025 · leading case: Meyers v. Bayer AG, Bayer Corp., 2007 WI 99 (Wis. 2007).
Meyers v. Bayer AG, Bayer Corp., 2007 WI 99 (Wis. 2007). “("Barr"), Hoechst Marion Roussel, Inc. ("HMR") and The Rugby Group ("Rugby"), which precluded Barr, HMR and Rugby from selling or marketing generic ciprofloxacin hydrochloride to compete with Cipro.”
Olstad v. Microsoft Corp., 2005 WI 121 (Wis. 2005). “Olstad (Ol-stad), suing individually and as class representative of all others similarly situated, appeals from a final order of the Circuit Court for Milwaukee County granting Microsoft Corporation's (Microsoft) motion for summary judgment and dismissing Olstad's action…”
E-Z Roll Off, LLC v. Cnty. of Oneida, 2011 WI 71 (Wis. 2011). “00 to Oneida County for each ton of municipal solid waste it delivered to the Facility, brought suit against Oneida County alleging that the agreement created an illegal restraint of trade in violation of Wis. Stat. § 133.03 (1) (2005-06). 2 The circuit court, the Honorable…”
Conley Publ'g Grp. Ltd. v. Journal Commc'ns, Inc., 2003 WI 119 (Wis. 2003). “209 (1993), be adopted as the law in Wisconsin governing predatory pricing under Wis. Stat. § 133.03 ? Second, does the federal rule governing the admissibility of expert opinion testimony set forth in Daubert v.”
Emergency One, Inc. v. Waterous Co., Inc., 23 F. Supp. 2d 959 (E.D. Wis. 1998). “Defendants have moved to dismiss all state claims brought under Wis. Stat. §§ 133.03 and 100.20 (counts X-XVIII of the amended complaint), arguing principally that the complaint alleges predominantly interstate transactions not covered by Chapter 133.”
Town of Neenah Sanitary Dist. No. 2 v. City of Neenah, 2002 WI App 155 (Wis. Ct. App. 2002). “The court further determined that the City's actions did not violate Wisconsin's antitrust provision, Wis. Stat. § 133.03 (1999-2000). 1 We affirm both rulings.”
Prentice v. Title Ins. Co. of Minnesota, 500 N.W.2d 658 (Wis. 1993). “[1] and sec. 133.03, Stats. [2] by agreeing to fix the prices of title insurance and related services.”
IDX Sys. Corp. v. Epic Sys. Corp., 165 F. Supp. 2d 812 (W.D. Wis. 2001). “Defendant UWMF’s Claim for Declaratory Judgment on the Validity of Plaintiff’s Contract Defendant UWMF seeks a declaration that the confidentiality provisions in 1986 and the 1989 contracts unreasonably restrain trade contrary to Wis. Stat. § 133.03 and thus are invalid and…”
Eichenseer v. Madison-Dane Cnty. Tavern League, Inc., 2008 WI 38 (Wis. 2008). “(collectively, the defendants) of horizontal price-fixing violations under Wis. Stat. § 133.03 (1) 2 because, in response to pressure from city government to ban all drink specials after 8 p.”
Cnty. of Milwaukee v. Williams, 2007 WI 69 (Wis. 2007). “[15] Wis. Stat. § 133.03 no longer applies "to ambulance service contracted for under ss.”
Sheet Metal Workers Local 441 Health & Welfare Plan v. Glaxosmithkline, PLC, 737 F. Supp. 2d 380 (E.D. Pa. 2010). “” Wis. Stat. § 133.03 (1). However, GSK fails to address subsection 2 of section 133.”
Ashley Furniture Indus., Inc. v. Packaging Corp. of Am., 275 F. Supp. 3d 957 (W.D. Wis. 2017). “14 provides for recovery of “[a]ny payment made upon, under or pursuant to” a “contractf ] or agreement ] made by any person while a member of any combination or conspiracy” in restraint of trade prohibited by Wis. Stat. § 133.03 . As previously discussed, while the Wisconsin…”
— Wis. Stat. § 133.03(1) — 12 cases
E-Z Roll Off, LLC v. Cnty. of Oneida, 2011 WI 71 (Wis. 2011). “00 to Oneida County for each ton of municipal solid waste it delivered to the Facility, brought suit against Oneida County alleging that the agreement created an illegal restraint of trade in violation of Wis. Stat. § 133.03 (1) (2005-06). 2 The circuit court, the Honorable…”
Meyers v. Bayer AG, 143 F. Supp. 2d 1044 (E.D. Wis. 2001).
Amoco Oil Co. v. Cardinal Oil Co., Inc., 535 F. Supp. 661 (E.D. Wis. 1982).
Am. Med. Transp. of Wisconsin, Inc. v. Curtis-Universal, Inc., 435 N.W.2d 286 (Wis. Ct. App. 1988).
Am. Med. Transp. of Wisconsin, Inc. v. Curtis-Universal, Inc., 452 N.W.2d 575 (Wis. 1990).
— Wis. Stat. § 133.03(2) — 5 cases
Lerma v. Univision Commc'ns, Inc., 52 F. Supp. 2d 1011 (E.D. Wis. 1999).
Meyers v. Bayer AG, Bayer Corp., 2007 WI 99 (Wis. 2007). “("Barr"), Hoechst Marion Roussel, Inc. ("HMR") and The Rugby Group ("Rugby"), which precluded Barr, HMR and Rugby from selling or marketing generic ciprofloxacin hydrochloride to compete with Cipro.”
Conley Publ'g Grp. Ltd. v. Journal Commc'ns, Inc., 2003 WI 119 (Wis. 2003). “209 (1993), be adopted as the law in Wisconsin governing predatory pricing under Wis. Stat. § 133.03 ? Second, does the federal rule governing the admissibility of expert opinion testimony set forth in Daubert v.”
Curtis Universal, Inc. v. Sheboygan Emergency Med. Servs., Inc., 844 F. Supp. 492 (E.D. Wis. 1994).
Am. Med. Transp. of Wisconsin, Inc. v. Curtis-Universal, Inc., 435 N.W.2d 286 (Wis. Ct. App. 1988).
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