Opinion by Judge DWYER; Dissent by Judge PAEZ.

I. INTRODUCTION

In this antitrust case originally brought in state court under the Cartwright Act, Cal. Bus. & Prof.Code §§ 16700-16770, the plaintiff milk producers 2 claim that the defendant cheese makers 3 conspired successfully to depress the prices they paid for milk produced in California. The alleged price fix among buyers was accomplished in an unusual way: through a now-defunct auction agency called the National Cheese Exchange (“NCE”), the cheese makers are said to have rigged the price for bulk cheese in order to depress their acquisition costs both for that commodity and for milk. California milk prices were targeted and restrained in that the NCE bulk cheese price “determined the cost of fluid milk.” That allegation, as the parties’ briefs confirm, means that the California Department of Food & Agriculture (“CDFA”) used the reported NCE bulk cheese price in its formula for setting the “support” (i.e., minimum) price for milk produced in that state. Thus, the alleged price-fixing that controlled the NCE bulk cheese price was intended to, and did, depress the California milk price as well. The milk producers claim that as a result they received less for their product than they would have received but for the unlawful price restraint. The cheese makers removed the case to federal court on the basis of diversity jurisdiction, see 28 U.S.C. § 1332 , and then moved pursuant to Fed. R.Civ.P. 12(b)(6) to dismiss for failure to state a claim on which relief could be granted. The district court, without hearing argument, issued a one-line order granting the motion to dismiss, and the milk producers filed a timely notice of appeal. Finding that this court has jurisdiction, and that the complaint adequately states claims under California law, we reverse and remand except as to one claim that has been abandoned.

3.The defendants are Kraft Foods, Inc. ("Kraft”), Alpine Lace Brands, Inc., and Borden, Inc. The district court dismissed the action as to a fourth defendant, National Cheese Exchange, for lack of personal jurisdiction; the milk producers have expressly waived any appeal from that order.

*983 II. JURISDICTION UNDER 28 U.S.C. § 1291

This court has jurisdiction of appeals from “all final decisions” of the district court. 28 U.S.C. § 1291 . No party has argued that jurisdiction is absent, but we must address the issue sua sponte. WMX Technologies, Inc. v. Miller, 104 F.3d 1133, 1135 (9th Cir.1997) (en banc).

The cheese makers’ motion in the district court was styled a motion to dismiss “the complaint” rather than “the action.” An order granting such a motion must be accompanied by leave to amend unless amendment would be futile. Lopez v. Smith, 203 F.3d 1122, 1127 (9th Cir. 2000). No such leave was granted here. “Ordinarily an order dismissing the complaint rather than dismissing the action is not a final order and thus not appealable. However, ‘[i]f it appears that the district court intended the dismissal to dispose of the action, it may be considered final and appealable.’ Hoohuli v. Ariyoshi, 741 F.2d 1169 , 1171 n. 1 (9th Cir.1984).” Gerritsen v. de la Madrid Hurtado, 819 F.2d 1511, 1514 (9th Cir.1987). Accord Martinez v. Gomez, 137 F.3d 1124, 1125 (9th Cir.1998) (“[I]t is clear that there is nothing further [the plaintiff] can do and the district court must have intended this order to end the case. Therefore, we treat the dismissal as a final order.”).

The record here shows that the district court intended its order to end the case. Although the cheese makers sought dismissal of the complaint, they repeatedly argued that the plaintiffs not only did not, but “cannot,” allege essential parts of an antitrust or unfair competition claim. The milk producers opposed the motion on the merits and, in the alternative, asked leave to amend “unless it is determined that no possible amendment would cure the complaint’s deficiencies.” The district court’s order reads simply: “It is Ordered that the motions to dismiss be, and hereby are, Granted.” This ruling necessarily entailed a denial of the alternative request for leave to amend and a determination, in the words of Lopez, 203 F.3d at 1127 , “that the pleading could not possibly be cured by the allegation of other facts.” Thus the district judge must have intended the dismissal order to end the case.

We have so held in several earlier cases. In Gerritsen we said: “Failure to allow leave to amend supports an inference that the district court intended to make the order final. Furthermore, the court’s intention of finality is evinced by its apparent conclusion that amendment of the complaint would not save the action.” 819 F.2d at 1514 (citations omitted). Accord Hoohuli, 741 F.2d at 1171, n. 1 ; Martinez, 137 F.3d at 1125-26 ; Scott v. Eversole Mortuary, 522 F.2d 1110, 1112 (9th Cir.1975).

The inference that finality was intended is especially strong here in light of the milk producers’ explicit request for leave to amend unless the court determined that no possible amendment would avoid dismissal. No one has suggested an amendment that could change the district court’s ruling.

Also probative is the understanding of the district court clerk that a final dismissal was ordered. The clerk’s docket entry describes the dismissal order as “terminating case.” A “JS-6” stamp on the order shows that the clerk reported the case as terminated to the Administrative Office of the United States Courts. See District Court Clerks Manual § 4.09b. The parties’ understanding has been the same, as reflected in their briefs on appeal. 4

*984 We conclude that the district court intended its order to be a final dismissal. Accordingly, this court has jurisdiction on appeal under 28 U.S.C. § 1291 .

III. STANDARD OF REVIEW

We review de novo the district court’s order of dismissal for failure to state a claim. See Wyler Summit Partnership v. Turner Broad. Sys., Inc., 135 F.3d 658 , 661 (9th Cir.1998). A motion to dismiss for failure to state a claim may not be granted “unless it appears beyond doubt that the plaintiff can prove no set of facts in support of his claim which would entitle him to relief.” Conley v. Gibson, 355 U.S. 41, 45-46 , 78 S.Ct. 99 , 2 L.Ed.2d 80 (1957). In ruling on such a motion, “the court must presume all factual allegations of the complaint to be true and draw all reasonable inferences in favor of the non-moving party.” Usher v. City of Los Angeles, 828 F.2d 556, 561 (9th Cir.1987). The complaint need not set out the facts in detail; what is required is a “short and plain statement of the claim showing that the pleader is entitled to relief.” Fed. R.Civ.P. 8(a); La Salvia v. United Dairymen, 804 F.2d 1113 , 1116 (9th Cir.1986). Antitrust cases are not to be judged by a higher or different pleading standard than other cases. See Hunt-Wesson Foods, Inc. v. Ragu Foods, Inc., 627 F.2d 919, 924 (9th Cir.1980). An antitrust plaintiff “need only allege sufficient facts from which the court can discern the elements of an injury resulting from an act forbidden by the antitrust laws.” Cost Management Servs., Inc. v. Washington Natural Gas Co., 99 F.3d 937, 950 (9th Cir.1996) (quoting Newman v. Universal Pictures, 813 F.2d 1519, 1522 (9th Cir.1987)).

IV. ALLEGATIONS OF THE COMPLAINT

The complaint sets out three claims. The first, naming all defendants, alleges a combination in restraint of trade in violation of the Cartwright Act, Cal. Bus. & Prof.Code § 16720. The second, also naming all defendants, alleges that the combination in restraint of trade, and acts done pursuant to it, violated the Unfair Competition Act, Cal. Bus. & Prof.Code § 17200. The third, naming Kraft only, alleges that Kraft violated the Unfair Competition Act by monopolizing and attempting to monopolize.

The third claim is deemed abandoned because the milk producers have not opposed its dismissal in their briefs and argument to this court. See Fed. R.App. P. 28(a)(9)(A) (requiring that the appellant’s brief contain “appellant’s contentions and the reasons for them”). See also Essery v. Department of Transp., 857 F.2d 1286 , 1288 n. 1 (9th Cir.1988) (“Nowhere does [appellant] argue that the [agency] erred in finding that he violated Sections 91.79(a) and (b).... That issue is therefore deemed abandoned.”). The first and second claims are at issue in this appeal.

For present purposes, the key allegations of the complaint are as follows: The plaintiff milk producers are “residents and citizens of California who have sold milk directly or indirectly to one or more of the defendants”; the defendant cheese makers purchase bulk cheese and milk for use in their products; NCE, in Wisconsin, operated the only national cash auction market for bulk cheese; the cheese makers “purchased substantial quantities of milk from plaintiffs and the members of the class, either directly or indirectly”; the cheese makers “did not compete and ... instead acted together to suppress the cost of milk purchased by them from plaintiffs and the members of the class”; “[b]y collusively manipulating NCE prices to levels lower than would prevail under conditions of free and open competition, [the cheese makers] lowered their procurement costs for bulk cheese bought off the NCE pursuant to NCE-based formula prices”; the NCE prices “determined the cost of fluid milk used by Kraft in its cheese plants”; the cheese makers formed a combination “in unreasonable restraint of trade and commerce” in violation of the Cartwright Act; the terms of the unlawful combination included “depressing, fixing, pegging, *985 stabilizing and maintaining prices paid for milk used in the manufacture of cheese”; as an intended result “prices paid by the defendants and their co-conspirators for milk were fixed, depressed, maintained and stabilized at artificially low and at non-competitive levels”; “competition for the purchase of milk in California was unreasonably restrained”; the cheese makers “have been unjustly enriched as a result of their wrongful conduct and ... unfair competition”; and the plaintiffs and class members “received less for milk than they otherwise would have received in the absence of the defendants’ unlawful conduct.”

The complaint details how the cheese makers allegedly did these things. The milk producers seek treble damages, an injunction, and other relief.

V. SUFFICIENCY OF THE COMPLAINT

In the absence of a statement by the district court of reasons for the dismissal, the cheese makers on appeal raise a variety of arguments. They contend that the complaint fails to plead antitrust injury and antitrust standing as required by the Cartwright Act; that relief is barred by the filed rate doctrine; that the Commerce Clause precludes application of California’s antitrust statute in this context; and that the milk producers’ related claims under the state’s unfair competition statute also must be dismissed. We consider these arguments in light of the rules, summarized above, governing motions to dismiss for failure to state a claim.

A. Cartwright Act and Sherman Act

The Cartwright Act, adopted in 1907, and the Sherman Act, adopted in 1890, have in common the goal of prohibiting trade-restraining combinations and monopolies and thereby preserving competition. The federal statute’s purpose is stated in Northern Pacific Railway v. United States, 356 U.S. 1, 4 , 78 S.Ct. 514 , 2 L.Ed.2d 545 (1958):

The California statute’s goal is described in Exxon Corp. v. Superior Court, 51 Cal. App.4th 1672, 1680 , 60 Cal.Rptr.2d 195 (1997):

There are, however, differences in statutory wording and legislative history that lead, in some respects, to different results. In State of California ex rel. Van de Kamp v. Texaco, Inc., 46 Cal.3d 1147, 1164 , 252 Cal.Rptr. 221 , 762 P.2d 385 (1988), the court held:

Thus, federal antitrust precedents are properly included in a Cartwright Act analysis, but their role is limited: they are “often helpful” but not necessarily decisive.

*986 B. Buyers’ Price-Fixing Combinations as Per Se Violations

The Sherman Act prohibits “[e]very contract, combination ... or conspiracy, in restraint of trade.” 15 U.S.C. § 1 . The Cartwright Act prohibits, among other things, any combination “[t]o prevent competition in [the] sale or purchase of ... any commodity” or to “[a]gree in any manner to keep the price of ... [any] commodity ... at a fixed or graduated figure.” Cal. Bus. & Prof.Code § 16720(c) and (e)(2).

Under both statutes, certain types of collusive conduct are held to be so destructive of competition, and so devoid of redeeming value, that they are conclusively presumed to be unreasonable — i.e., they are per se violations. See Northern Pac. Ry., 356 U.S. at 5 , 78 S.Ct. 514 ; People v. Santa Clara Valley Bowling Proprietor’s Ass’n, 238 Cal.App.2d 225, 235 , 47 Cal.Rptr. 570 (1965).

Foremost in the category of per se violations is horizontal price-fixing among competitors. This long-established rule was explained by the Supreme Court in United States v. Trenton Potteries Co., 273 U.S. 392, 397 , 47 S.Ct. 377 , 71 L.Ed. 700 (1927): “The aim and result of every price-fixing agreement, if effective, is the elimination of one form of competition.” See also NYNEX Corp. v. Discon, Inc., 525 U.S. 128, 133 , 119 S.Ct. 493 , 142 L.Ed.2d 510 (1998). “Restrictions on price and output are the paradigmatic examples of restraints of trade that the Sherman Act was intended to prohibit.” NCAA v. Board of Regents, 468 U.S. 85, 107-08 , 104 S.Ct. 2948 , 82 L.Ed.2d 70 (1984).

The same rule applies in California: “Under both California and federal law, agreements fixing or tampering with prices are illegal per se.” Oakland-Alameda County Builders Exch. v. F.P. Lathrop Constr. Co., 4 Cal.3d 354, 363 , 93 Cal.Rptr. 602 , 482 P.2d 226 (1971).

The California statute explicitly makes price fixing by buyers unlawful. See Cal. Bus. & Prof.Code § 16720(c) (prohibiting any combination to prevent competition in the “sale or purchase of any commodity” (emphasis added)). The federal decisional law, based on a more generally worded statute, reaches the same result. See United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 223 , 60 S.Ct. 811 , 84 L.Ed. 1129 (1940) (“A combination formed for the purpose and with the effect of raising, depressing, fixing, pegging, or stabilizing the price of a commodity in interstate or foreign commerce is illegal per se.”) (emphasis added); Mandeville Island Farms v. American Crystal Sugar Co., 334 U.S. 219, 235 , 68 S.Ct. 996 , 92 L.Ed. 1328 (1948) (“It is clear that the agreement is the sort of combination condemned by the Act, even though the price-fixing was by purchasers, and the persons specially injured under the treble damage claim are sellers, not customers or consumers.”). See also Harkins Amusement Enters., Inc. v. General Cinema Corp., 850 F.2d 477 , 487 (9th Cir.1988) (“Concerted action to eliminate competitive bidding violates the Sherman Act.”).

When a per se violation such as horizontal price fixing has occurred, there is no need to define a relevant market or to show that the defendants had power within the market. See, e.g., FTC v. Superior Ct. Trial Lawyers Ass’n, 493 U.S. 411 , 435-36 & n. 19, 110 S.Ct. 768 , 107 L.Ed.2d 851 (1990). The California Supreme Court has held, under the Cartwright Act, that competitors who agree to fix prices are liable under the per se rule “[e]ven though the members of the price-fixing group were in no position to control the market.” Mailand v. Burckle, 20 Cal.3d 367, 376 , 143 Cal.Rptr. 1 , 572 P.2d 1142 (1978) (quoting Socony-Vacuum Oil Co., 310 U.S. at 221 , 60 S.Ct. 811 ).

The cheese.makers cite In re Beef Industry Antitrust Litigation, 907 F.2d 510 (5th Cir.1990), for the proposition that the milk producers’ claims must fail for lack of a showing that the cheese makers had the power to suppress total industry demand for milk, not just their own demand. The court there, noting that the alleged conspirators were only two of the four major buyers of cattle, described the plaintiffs’ *987 theory as “economically unfeasible,” and said that

Id. at 516 . We need not decide whether In re Beef is consistent with controlling Supreme Court precedent or California law because the case is inapposite. First, the court there found that the plaintiffs had failed to submit sufficient proof of a conspiracy, id. at 514 , a question not involved in the present Rule 12(b)(6) motion. Second, there was no allegation that the defendant cattle purchasers were able to, and did, concertedly depress a statewide commodity price by manipulating a minimum price formula. That claim here is exactly contrary to the In re Beef holding that the alleged conspiracy “could not succeed.” According to the present complaint, the conspiracy had the means to, and did, succeed.

C. Antitrust Standing

Private suits to enforce the Sherman Act are authorized by Section 4 of the Clayton Act, 15 U.S.C. § 15 (a), which provides that “any person who shall be injured in his business or property by reason of anything forbidden in the antitrust laws may sue therefor ... and shall recover threefold the damages by him sustained, and the cost of suit, including a reasonable attorney’s fee.” Despite the apparent breadth of the phrase “any person,” the Supreme Court has held that Congress did not intend to afford a remedy to everyone injured by an antitrust violation simply on a showing of causation. The plaintiff must have “antitrust standing.” To determine whether that requirement is met, the court must “evaluate the plaintiffs harm, the alleged wrongdoing by the defendants, and the relationship between them.” Associated Gen. Contractors of California, Inc. v. California State Council of Carpenters, 459 U.S. 519, 535 , 103 S.Ct. 897 , 74 L.Ed.2d 723 (1983). In American Ad Management, Inc. v. General Tel. Co., 190 F.3d 1051 , 1054-55 (9th Cir.1999), this court summarized the factors relevant to antitrust standing as follows: “(1) the nature of the plaintiffs alleged injury; that is, whether it was the type the antitrust laws were intended to forestall; (2) the directness of the injury; (3) the speculative measure of the harm; (4) the risk of duplicative recovery; and (5) the complexity in apportioning damages.”

Antitrust standing is required under the Cartwright Act. See Rolling v. Dow Jones & Co., 137 Cal.App.3d 709, 723 , 187 Cal.Rptr. 797 (1982). As shown below, however, California law affords standing more liberally than does federal law.

(a) Antitrust Injury

The first factor—the “nature of the’ plaintiffs alleged injury”—requires a showing of “antitrust injury,” i.e., “injury of the type the antitrust laws were intended to prevent and that flows from that which makes defendants’ acts unlawful.” Atlantic Richfield Co. v. USA Petroleum Co., 495 U.S. 328, 334 , 110 S.Ct. 1884 , 109 L.Ed.2d 333 (1990). As this court stated in American Ad Management, 190 F.3d at 1055:

The complaint here plainly alleges unlawful conduct, i.e., a per se antitrust violation, and that the conduct was intended to and did injure the plaintiffs. 5 Since *988 the plaintiffs allegedly were subjected to artificially depressed milk prices, the injury flows “from that which makes the conduct unlawful,” i.e., from the collusive price manipulation itself. The cheese makers argue, however, that the fourth requirement — that the injury be “of the type the antitrust laws were intended to prevent”' — • is unmet. They say, in substance, that a conspiracy to depress prices would not harm consumers but benefit them, because reduced milk acquisition costs would mean lower cheese manufacturing costs and, therefore, lower prices for cheese products. They contend that “the alleged conduct actually increased competition in the milk market,” and that “injury from selling at lower, more competitive prices is simply not enough.”

The fallacy of this argument becomes clear when we recall that the central purpose of the antitrust laws, state and federal, is to preserve competition. It is competition — not the collusive fixing of prices at levels either low or high — that these statutes recognize as vital to the public interest. The Supreme Court’s references to the goals of achieving “the lowest prices, the highest quality and the greatest material progress,” Northern Pac. Ry., 356 U.S. at 4 , 78 S.Ct. 514 , and of “assuring] customers the benefits of price competition,” Associated Gen., 459 U.S. at 538 , 103 S.Ct. 897 , do not mean that conspiracies among buyers to depress acquisition prices are tolerated. Every precedent in the field makes clear that the interaction of competitive forces, not price-rigging, is what will benefit consumers. “[0]ur prior cases,” the Court noted in Associated General, “have emphasized the central interest in protecting the economic freedom of participants in the relevant market.” 459 U.S. at 538 , 103 S.Ct. 897 . In California, similarly, “The public interest requires free competition so that prices be not dependent upon an understanding among suppliers of any given commodity, but upon the interplay of the economic forces of supply and demand.” Speegle v. Board of Fire Underwriters, 29 Cal.2d 34, 44 , 172 P.2d 867 (1946).

The cheese makers’ argument also confuses vertical price fixing (e.g., resale prices imposed by a manufacturer on its distributors) with horizontal price fixing (collusive price setting or stabilization by competitors). Under federal law, vertical arrangements that set minimum prices are illegal per se while those that set maximum prices are tested under the rule of reason and may or may not be deemed to have anticompetitive consequences. See State Oil Co. v. Khan, 522 U.S. 3 , 118 S.Ct. 275 , 139 L.Ed.2d 199 (1997). Horizontal price fixing is a per se violation regardless of whether the prices set are minimum or maximum. See Arizona v. Maricopa County Medical Society, 457 U.S. 332 , 102 S.Ct. 2466 , 73 L.Ed.2d 48 (1982). The defendants rely largely on cases that involved claims by competitors — a category much different from that of claims between buyers and sellers. When horizontal price fixing causes buyers to pay more, or sellers to receive less, than the prices that would prevail in a market free of the unlawful trade restraint, antitrust injury occurs. This is seen most often in claims by overcharged buyers; as to underpaid sellers it is less common in the reported cases, but is equally true. As stated in a leading text, 2 Phillip E. Areeda & Herbert Hovenkamp, Antitrust Law ¶ 375b at 297 (rev. ed.1995):

To hold otherwise would be contrary to long-established antitrust law. 6

Antitrust injury requires that the “injured party be a participant in the same market as the alleged malefactors.” American Ad Management, 190 F.3d at 1057 (quoting Bhan v. NME Hospitals, Inc., 772 F.2d 1467, 1470 (9th Cir.1985)). The defendants here contend that they are in one market (cheese) while the plaintiffs are in another (fluid milk). But the complaint’s allegations unmistakably place all parties in the milk market — the defendants as buyers and the plaintiffs as sellers — and even have them transacting business with each other. For present purposes those allegations must be accepted as true. •

(b) Directness of the Injury

The plaintiffs must prove injury in fact, and the claimed injury must be sufficiently direct. Under federal law, there must be “not a mere causal link, but a direct effect.” City of Pittsburgh v. West Penn Power Co., 147 F.3d 256, 268 (3d Cir.1998) (not direct where there was “no way to determine whether the rates the city will pay for electric service are or will be affected by the alleged actions”). To assess the directness of the plaintiffs injury, the court “look[s] to the chain of causation between [plaintiffs] injury and the alleged restraint in the market.” American Ad Management, 190 F.3d at 1058.

The cheese makers argue that the milk producers were free to sell their milk to others at higher prices than the minimum levels set by the CDFA. But that argument merely denies that the plaintiffs were damaged in fact. It does not speak to the complaint, which alleges that the plaintiffs were damaged when the defendants fixed milk prices at artificially low levels and thereby caused plaintiffs to “receive! ] less for milk than they otherwise would have received in the absence of the defendants’ unlawful conduct.” These disputed claims of causation and injury cannot be decided on a Rule 12(b)(6) motion.

The defendants also contend that since the market allegedly restrained was that for cheese, and the milk support price was set by a state agency, the chain of causation is too tenuous to support re- *990 covery. But that too overlooks what the complaint says — that the defendants were buyers in the milk market, that they conspired to depress the price of milk produced in California, and that they did so by rigging the NCE bulk cheese price at artificially low levels. ■ According to these allegations, the NCE price was a tool used by the conspirators to manipulate the California milk price. The result for purposes of antitrust injury analysis should be no different than if the cheese makers had conspired to report a fictitious NCE price in order to depress the milk price, which clearly would cause direct injury to the milk producers. See Woods Exploration & Producing Co. v. Aluminum Co. of Am., 438 F.2d 1286, 1296 (5th Cir.1971) (summary judgment reversed where Oil producers allegedly conspired to report false production data to state agency so as to increase production allowance); 7 City of Long Beach v. Standard Oil, 872 F.2d 1401 , 1408 (9th Cir.1989) (injury sufficiently direct notwithstanding federal price ceilings where ceilings allegedly were based on artificially low procurement prices collusively posted by defendants). Here, as in City of Long Beach, the defendants allegedly conspired successfully to subject the plaintiffs (their suppliers) to artificially low prices by reporting fixed prices to an agency. As the Supreme Court has stated, “the machinery employed by a combination for price-fixing is immaterial.” United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 223 , 60 S.Ct. 811 , 84 L.Ed. 1129 (1940). 8

That the alleged conspiracy restrained prices for two commodities — bulk cheese and milk — would not immunize the defendants against antitrust claims. The milk sellers, insofar as the alleged conspiracy was meant to and did reduce their sales prices, suffered a direct injury. Antitrust violations frequently entail multiple means and objectives (e.g., restraining both purchase prices and sales prices or boycotting to enforce price stabilization). See, e.g., FTC v. Superior Ct. Trial Lawyers Ass’n, 493 U.S. 411 , 110 S.Ct. 768 , 107 L.Ed.2d 851 (1990); Denny’s Marina, Inc. v. Renfro Productions, Inc., 8 F.3d 1217, 1221 (7th Cir.1993); Ancar v. Sara Plasma, Inc., 964 F.2d 465 (5th Cir.1992). The law requires that every conspiracy be judged as a whole. This important rule was stated in Continental Ore Co. v. Union Carbide & Carbon Corp., 370 U.S. 690, 699 , 82 S.Ct. 1404 , 8 L.Ed.2d 777 (1962) (citations and internal quotations omitted):

Accord Beltz Travel Serv. v. International Air Transport Ass’n, 620 F.2d 1360, 1366-67 (9th Cir.1980). Thus, where a plaintiff is injured by one facet of a multi-faceted conspiracy he is entitled to damages regardless of whether the other facets of the defendants’ collusion had any economic impact on him. Washington State Bowling Proprietors Ass’n v. Pacific Lanes, Inc., 356 F.2d 371 (9th Cir.1966).

The extent to which antitrust injury is recognized under the Cartwright Act is enlarged, by statute, in comparison to federal law. The Act provides, at Calif. Bus. & Prof.Code § 16750(a) (emphasis added):

The last clause was added by the California legislature following the Supreme Court’s decision in Illinois Brick Co. v. Illinois, 431 U.S. 720 , 97 S.Ct. 2061 , 52 L.Ed.2d 707 (1977), which limited the ability of indirect purchasers to recover , damages under the Sherman and Clayton Acts. As a result, “the more restrictive definition of ‘antitrust injury’ under federal law does not apply” to the Cartwright Act. Cellular Plus, Inc. v. Superior Court, 14 Cal.App.4th 1224, 1234 , 18 Cal.Rptr.2d 308 (1993). The Cellular Plus court, affording standing to agents who allegedly lost sales due to prices having been artificially inflated by their principals’ price-fixing, said that “[t]he exact parameters of ‘antitrust injury’ under section 16750 have not yet been established” but that “the scope of that term is broader” than under federal law. Id. 9

(c) Speculative Nature of Harm

The cheese makers argue that because other factors influence milk prices, the harm to plaintiffs is speculative. See Associated Gen. Contractors, 459 U.S. at 542 , 103 S.Ct. 897 (“Partly because the alleged effects on the [plaintiff] may have been produced by independent factors, the [plaintiffs] damages claim is also highly speculative.”). This argument fails in light of the complaint’s allegation that the rigged NCE price controlled the price of fluid milk produced in California. Whether experts will be able to measure the difference between the allegedly restrained price for milk and the price that would have prevailed but for the antitrust violation remains to be seen; in deciding a Rule 12(b)(6) motion we are dealing only with the complaint’s allegations, which in this instance do not make the claim speculative.

(d) The Risk of Duplicative Recovery

There appears to be no risk of this nature. The allegedly underpaid plaintiffs sustained the injury. The cheese makers *992 have not suggested anyone else who could sue to recover damages for the underpayment.

. (e) Complexity in Apportioning Damages

This factor comes into play when multiple classes or layers of claimants seek, or might seek, compensation. It is totally absent here.

In summary, all elements of antitrust standing are satisfied on the face of the present complaint.

D. The Filed Rate Doctrine

California has a regulatory scheme for the marketing of milk. The legislature determined that it was “essential to establish minimum producer prices at fair and reasonable levels so as to generate reasonable producer incomes that will promote the intelligent and orderly marketing of market milk ... and that minimum producer prices established [by the director of the CDFA (the ‘Director’) ] should not be unreasonably depressed because other factors have affected the levels of retail prices paid by consumers.” Cal. Food & Agrie. Code § 61802 (h). To achieve these ends the Director is authorized “to prescribe marketing areas and to determine minimum prices” to be paid to milk producers. Cal. Food & Agrie. Code § 61805 . Between 1989 and 1997, the period of claimed injury to the plaintiffs, the Director used the NCE bulk cheese price as part of a formula to compute the minimum price of milk in California. By rigging the NCE price, according to the complaint, the cheese makers artificially depressed the minimum price for milk, to plaintiffs’ damage. The cheese makers now argue that the filed rate doctrine requires dismissal of the action.

The filed rate doctrine originated in Keogh v. Chicago & Northwestern Railway, 260 U.S. 156 , 43 S.Ct. 47 , 67 L.Ed. 183 (1922), where the Court held that a private shipper could not recover treble damages against railway companies that had set uniform rates duly filed with, and approved by, the Interstate Commerce Commission. Two rationales were offered. First, the regulatory scheme allowed the recovery of damages for illegal rates in proceedings before the ICC; Congress presumably would not have intended a second remedy. Second, carrier rate regulation was primarily intended to prevent the charging of discriminatory rates, an objective which would be disserved by affording antitrust recovery to some shippers but not all. Although the doctrine has been questioned by many including the Supreme Court itself, it lives on to a limited extent. See Square D Co. v. Niagara Frontier Tariff Bureau, Inc., 476 U.S. 409 , 106 S.Ct. 1922 , 90 L.Ed.2d 413 (1986); MCI Telecommunications Corp. v. AT & T Co., 512 U.S. 218, 234 , 114 S.Ct. 2223 , 129 L.Ed.2d 182 (1994). Where damages are sought under the federal antitrust laws, the doctrine may preclude relief if the challenged rates or prices were set by either federal or state regulatory authorities. See Wegoland Ltd. v. NYNEX Corp., 27 F.3d 17 (2d Cir.1994). Where damages are sought under a state law, it may apply if the challenged rates or prices were set by a federal regulatory authority. See, e.g., Duggal v. G.E. Capital Communications Serv., 81 Cal.App.4th 81, 87-88 , 96 Cal.Rptr.2d 383 (2000); County of Stanislaus v. Pacific Gas & Elec. Co., 114 F.3d 858 , 866 (9th Cir.1997) (“[T]he filed rate doctrine bars all claims — state and federal' — that attempt to challenge a rate that a federal agency has reviewed and filed.”)

This case, however, involves only a state antitrust law being applied where an agency of that state has set a commodity price that, according to the complaint, was wrongfully depressed by manufacturers who collusively manipulated data submitted to and used by the agency. Whether damages can be awarded to the injured parties is a matter of state law. California has held, in contrast to federal law, that no filed rate doctrine exists as a bar. In Cellular Plus, Inc., v. Superior Court, 14 Cal.App.4th 1224 , 18 Cal.Rptr.2d 308 *993 (1993), the defendant telephone service providers contended that the filed rate doctrine shielded them because the prices they charged for service — prices which the plaintiffs claimed were the result of a horizontal price-fixing conspiracy — had been filed with and approved by the California Public Utilities Commission. Id. at 1240 , 18 Cal.Rptr.2d 308 . The state court agreed that the filed rate doctrine would avail defendants if it applied, but held that under the Cartwright Act no such doctrine would bar recovery:

Id. at 1241-42 , 18 Cal.Rptr.2d 308 .

The Cellular Plus court set out a number of reasons for not following Keogh and Square D, see 14 Cal.App.4th at 1242 , 18 Cal.Rptr.2d 308 , and concluded that to deny standing would “implicitly ... encourage[ ] regulated companies to engage in anticompetitive price fixing activities.” Id. at 1243 , 18 Cal.Rptr.2d 308 . While the facts alleged here differ in some respects from those asserted in Cellular Plus, there is no reason to think that California would apply the filed rate doctrine that it has so clearly rejected. As we noted in County of Stanislaus, 114 F.3d at 866, “Cellular Plus merely declined to create a state filed rate doctrine where rates filed with the [state agency] were not subject to federal review.” 10

In a related argument, the cheese makers contend that the Director in 1989 and 1995 considered and rejected claims that the NCE bulk cheese price was rigged. The milk producers agree that the Director decided to keep the NCE price in the California minimum milk price formula, but deny that he exonerated the defendants or made any findings that would permit or justify price-fixing. This dispute, like others raised by the parties, has no place in deciding a motion under Rule 12(b)(6). We express no opinion as to the merits of the argument because, however it might be resolved at a later stage, it cannot support a dismissal for failure to state a claim.

E. The Commerce Clause

The cheese makers argue that the milk producers’ action, if allowed to proceed, would run afoul of the Commerce Clause, U.S. Const, art. I, § 8, cl. 3. But the Supreme Court has made clear that neither the Sherman Act nor the Commerce Clause preempts state antitrust laws. See, e.g., California v. ARC Am. Corp., 490 U.S. 93 , 109 S.Ct. 1661 , 104 L.Ed.2d 86 (1989). On point is Exxon Corp. v. Governor of Maryland, 437 U.S. 117 , 98 S.Ct. 2207 , 57 L.Ed.2d 91 (1978), which concerned a Maryland statute designed to foster competition by requiring oil refiners to divest themselves of retail service stations and charge a uniform price to all stations they supplied. Id. at 121-22 , 98 S.Ct. 2207 . The refiners challenged the statute, arguing that the Commerce Clause precluded enforcement of the Maryland statute because the refiners were out-of-state companies whose out-of-state transactions should not be subjected to regulation by a state in which no refiners were located. The Supreme Court rejected the argument and upheld the right of states to apply their competition statutes unless lack of uniformity would impede the flow of goods. There is nothing to suggest that application of the Cartwright Act to prevent price-fixing by buyers of California milk would impede the flow of goods. The conduct complained of took place not only in Wisconsin, where NCE was locat *994 ed, but in California, where the cheese makers allegedly purchased milk at prices artificially depressed by their combination in restraint of trade. That being so, California may apply its antitrust and unfair competition statutes consistent with the Commerce Clause. 11

F. Unfair Competition Claim

The milk producers’ unfair competition claim is brought under California’s Unfair Competition Act, Cal. Bus. & Prof.Code § 17200, which prohibits “any unlawful, unfair or fraudulent business act or practice.” The cheese makers contend that because the antitrust claim must be dismissed, the unfair competition claim must fail as well because any finding of unfairness must be “tethered to some legislatively declared policy or proof of some actual or threatened impact on competition.” Cel-Tech Communications, Inc. v. Los Angeles Cellular Tel. Co., 20 Cal.4th 168 , 186-87, 83 Cal.Rptr.2d 548 , 973 P.2d 527 (1999). The argument must be rejected for three reasons:

First, the quoted statement in Cel-Tech was limited to claims of “unfairness to competitors,” a category of cases unlike the case at bar. Id.

Second, the argument must fail in any event because the milk producers’ antitrust claim survives the present challenge.

Third, a plaintiff may bring an unfair competition claim under California law unless some other provision bars the action by clearly permitting the conduct. See id. at 184, 83 Cal.Rptr.2d 548 , 973 P.2d 527 . The milk producers are not barred from pursuing their Cartwright Act and Unfair Competition Act claims together.

VI. CONCLUSION

It bears repeating that we are not concerned with which side will prevail at trial, or even with whether the milk producers’ claims will survive summary judgment. The cheese makers’ motion under Fed. R.Civ.P. 12(b)(6) tests only whether the complaint’s allegations are such that a set of facts within their scope could entitle the plaintiffs to relief. The present complaint satisfies that test.

REVERSED AND REMANDED as to claims one and two; AFFIRMED as to claim three. Plaintiffs/appellants will recover their costs in this court.

. The plaintiffs are Knevelbaard Dairies, a general partnership, and John and Sam Kne-velbaard. They sue for themselves and a putative class of others similarly situated. We express no opinion as to whether a class should be certified pursuant to Fed.R.Civ.P. 23.

. The milk producers say: "The district court demonstrated its intent to issue an appealable dismissal by directing that it be entered pursuant to the rule governing entry of judgments. See Martinez, v. Gomez, 137 F.3d 1124, 1126 (9th Cir.1998) (order of dismissal appealable when district court intended it to end the action).” The cheese makers say:

. The milk producers do not contend that they are exempt from the antitrust injury requirement because the cheese makers corn-mitted a per se violation, nor would any such contention be tenable. They argue only that *988 once a per se violation is proved they need not show market power, and in that they are correct (see supra Section V.B.); they still must prove injury in fact and antitrust injury.

. Brunswick Corp. v. Pueblo Bowl-O-Mat, Inc., 429 U.S. 477 , 97 S.Ct. 690 , 50 L.Ed.2d 701 (1977), cited by the cheese makers, is plainly inapplicable. In American Ad Management, 190 F.3d at 1056, we described that case as follows:

Atlantic Richfield Co., 495 U.S. 328 , 110 S.Ct. 1884 , 109 L.Ed.2d 333 , involved a vertical maximum price arrangement. A gasoline retailer complained that low retail prices imposed by an oil company on its dealers, competitors of the plaintiff, were depriving the plaintiff of business. The Court held that the claimed injury did not stem "from a competition-reducing aspect or effect of the defendants' behavior.” Here, in contrast to these and other cases cited by defendants, the claimed injury flows directly from that which makes the defendants' conduct unlawful.

. Other cases holding that antitrust claims may be pursued by parties injured as the result of the knowing and collusive submission of false information to a' government agency include Clipper Exxpress v. Rocky Mountain Motor Tariff Bureau, 690 F.2d 1240, 1261 (9th Cir.1982); Israel v. Baxter Labs., 466 F.2d 272 (D.C.Cir.1972); Outboard Marine Corp. v. Pezetel, 474 F.Supp. 168 (D.Del.1979); and Litton Sys. v. AT & T, 487 F.Supp. 942, 956 (S.D.N.Y.1980) ("The system of administrative supervision is not undercut but is complemented and reinforced by affording judicial relief for cynical evasion or corruption of that system for unfair competitive advantage”).

. To constitute horizontal price fixing, the agreement among competitors need not involve the ultimate price. In Socony-Vacuum, the Court condemned a concerted program by oil companies to purchase surplus gasoline on the spot market to prevent prices from falling, noting that even if the conspirators "were in no position to control the market, to the extent that they raised, lowered, or stabilized prices they would be directly interfering with the free play of market forces.” 310 U.S. at 221 , 60 S.Ct. 811 .. See also Catalano, Inc. v. Target Sales, Inc., 446 U.S. 643, 648 , 100 S.Ct. 1925 , 64 L.Ed.2d 580 (1980) (agreement to standardize credit terms "falls squarely within the traditional per se rule against price fixing”); Plymouth Dealers’ Ass'n v. United States, 279 F.2d 128 (agreement to use standard trade-in allowances); Northwestern Fruit Co. v. A. Levy & J. Zentner Co., 665 F.Supp. 869 (E.D.Cal.1986) (use of standardized cooling and pelletizing charge).

. The complaint alleges that the plaintiffs "sold milk directly or indirectly to one or more of the defendants " and that the putative class is composed of "all persons who reside in the State of California and who sold milk, directly or indirectly, to any of the defendants during the period from January 1, 1988, to April 1997.” (Emphasis added.) The parties have not briefed, and we need not decide, whether milk sellers who sold to non-conspirator buyers, at prices claimed to be artificially low because of the market effects of defendants' conspiracy, would have standing to seek damages from defendants. There is a split of authority on that subject. See, e.g., In re Arizona Dairy Products Litigation, 627 F.Supp. 233, 235-36 (D.Ariz.1985) (standing granted); In re Copper Antitrust Litigation, 98 F.Supp.2d 1039 (W.D.Wis.2000) (standing granted); FTC v. Mylan Lab., Inc., 62 F.Supp.2d 25, 38-39 (D.D.C.1999) (standing denied); Gross v. New Balance Athletic Shoe, Inc., 955 F.Supp. 242, 245 (S.D.N.Y.1997) (standing denied); and the cases collected at ABA Section of Antitrust Law, Antitrust Law Developments 779 n. 128 (4th ed.1997).

. The cheese makers' reliance on Day v. AT & T Corp., 63 Cal.App.4th 325 , 74 Cal.Rptr.2d 55 (1998), is misplaced. That case involved rates filed with the Federal Communications Commission. See id. at 337 , 74 Cal.Rptr.2d 55 (“The net effect of imposing any monetary sanction on the respondents will be to effectuate a rebate, thereby resulting in discriminatory rates. As we have seen, this is a matter ■ which is strictly of federal concern under the [Federal Communications] Act, and is, therefore, barred by the filed rate doctrine.”).

. Cases holding that nondiscriminatory state economic regulation may be imposed despite an impact on interstate commerce are collected at ABA Section of Antitrust Law, Antitrust Developments, 745-46 (4th ed. 1997).

. Contrary to the majority's statement that the plaintiffs sought leave to amend unless the court determined no possible amendment would cure the complaint's deficiencies^] plaintiffs actually requested leave to amend "to determine if they can allege facts sufficient to meet the applicable legal standard set forth by this Court." This may seem a minor distinction, but to the extent the majority seeks to divine from the district court’s silence just what the court intended in granting defendants’ motion to dismiss, it is necessary to state accurately what plaintiffs sought if, as happened, the district court granted defendants' motion. The majority errs here. The plaintiffs wanted a chance to amend if the district court granted the motion. By granting the motion, the district court implicitly acknowledged plaintiffs' request, particularly given the absence of a statement that a sepa *997 rate judgment would be entered or otherwise ending the case.