The district court erred in modifying CACI 3405, which states that a plaintiff may prove the second element of an unreasonable course of conduct claim by proving either anticompetitive purpose or effect, and CACI 3411, which lists factors for a jury to consider in weighing the anticompetitive purposes or effects of a defendant’s conduct. The district court removed the word “purpose” from both instructions, thus improperly disabling the jury from weighing whether defendant’s conduct was intended to have an anticompetitive effect. The Cartright Act and California Supreme Court decisions under it have long held that the rule of reason analysis tests whether the accused contract, combination or conspiracy had an anticompetitive purpose or effect. Consideration of anticompetitive purpose is an essential aspect of the rule of reason analysis under both the Cartwright Act and the Sherman Act. Anticompetitive purpose is one of several relevant factors that a trier of fact may consider in deciding the anticompetitive effect. By removing that permissible factor from the jury’s consideration, the district court committed reversible error. The district court also abused its discretion in excluding evidence relating to defendant’s conduct before the four year limitations period preceding the filing of the complaint. Pre-limitations conduct was relevant to prove plaintiff’s theory that Sutter switched from having its individual facilities negotiate separate contracts with HMOs to Sutter systemwide negotiations in order to gain leverage from several markets in which it held near monopolies on health care.