On June 7, 1996, on behalf of herself and all other retail consumers of CARB gasoline, Aguilar (P) filed an unverified complaint, with a demand for trial by jury, against the petroleum companies in the Superior Court of San Diego County. The complaint alleged violation of section 1 of the Cartwright Act (Stats. 1907, ch. 530, § 1, pp. 984-985, as amended, Bus. & Prof. Code, § 16720 et seq.), which is analogous to section 1 of the Sherman Act (Act of July 2, 1890, ch. 647, § 1, 26 Stat. 209, as amended, 15 U.S.C. § 1), asserting in substance that the petroleum companies had entered into an unlawful conspiracy to restrict the output of CARB gasoline and to raise its price--specifically, a conspiracy among competitors that is unlawful per se without regard to any of its effects. P also alleged facts for a derivative cause of action for violation of the unfair competition law ( Bus. & Prof. Code, § 17200 et seq.), asserting in substance that the conspiracy in question, even if not unlawful under the Cartwright Act, was unlawful at least under the unfair competition law itself. Ds denied all allegations. Ds moved the superior court for summary judgment. In support, they each presented evidence including declarations by officers or managers or similar employees with responsibility in the premises, generally stating on personal knowledge how the company made its capacity, production, and pricing decisions about CARB gasoline, asserting that it did so independently, and denying that it did so collusively with any of the others. P opposed the motions. In support, she presented evidence including the companies' gathering and dissemination of capacity, production, and pricing information, through the independently owned and operated Oil Price Information Service, or OPIS, and otherwise; their use of common consultants; and, perhaps most prominently, their execution of exchange agreements--under which, for example, two companies may trade, with or without a price differential, products of the same type in different geographical areas and/or at different times or products of different types in the same geographical area and/or at the same time--including any consequent activity, or lack of activity, in the spot market, where individual wholesale bulk sales and purchases are transacted. She also presented related evidence in the form of opinion by experts. The court granted summary judgment to Ds: there was no triable issue of material fact and that they were entitled to judgment as a matter of law. P moved the superior court for a new trial. In so doing, she challenged its judgment by challenging as erroneous its order granting the petroleum companies summary judgment. Specifically, among her grounds for a new trial was a claim that, in granting summary judgment as to her Cartwright Act cause of action, it made an 'error in law' in reading and applying Biljac as it did. The superior court issued an order granting a new trial. The court stated that it did indeed make an 'error in law.' In specifying its reasons, it stated that it did in fact misread and misapply Biljac to allow the petroleum companies to carry their initial burden of production to make a prima facie showing of the absence of any conspiracy as to her Cartwright Act cause of action by presenting evidence other than through declarations by each person responsible within each company for its capacity, production, and pricing decisions about CARB gasoline: it now read and applied Biljac to require declarations by each such person. Its order granting a new trial effectively vacated its judgment. Ds filed a notice of appeal in the superior court from its order granting a new trial. The Court of Appeal reversed the superior court's order granting a new trial and remanded the case to the superior court with directions to issue an order granting the petroleum companies summary judgment and, impliedly, to render judgment accordingly and cause entry thereof. The Court of Appeal concluded that the superior court's order granting a new trial was erroneous because it concluded that the superior court's order granting the petroleum companies summary judgment was not. The Court of Appeal determined that, as to P's Cartwright Act cause of action, the petroleum companies carried their burden of production to make a prima facie showing of the absence of any conspiracy, but P did not carry her shifted burden of production to make a prima facie showing of the presence of an unlawful one, her 'evidence' often being less than it was claimed to be. The Court of Appeal rejected the superior court's determination that it made an error in law in its reading and application of Biljac, finding no support therein for any requirement that the petroleum companies had to present evidence in the form of declarations by each person responsible within each company for its capacity, production, and pricing decisions about CARB gasoline. P petitioned for review.