Section 107(a) of the Comprehensive Environmental Response, Compensation, and Liability Act (“CERCLA”), 42 U.S.C. § 9601 et seq., imposes liability on certain private parties for the cleanup costs associated with a hazardous waste contamination. In turn, CERCLA Section 113(f), added by the Superfund Amendments and Reauthorization Act of 1986 (“SARA”), Pub.L. No. 99-499, 100 Stat. 1613 (1986), allows those responsible for cleanup costs to bring actions for contribution against one another as a means of apportioning fault. Metropolitan Water Reclamation District of Chicago (“Metropolitan Water”) has brought this action under both provisions, seeking to recover cleanup costs that it voluntarily incurred in remedying a parcel of property that it has leased for the past fifty years to Lake River Corporation (“Lake River”). Lake River’s parent, North American Galvanizing & Coatings, Inc. (“North American”), moved to dismiss Metropolitan Water’s complaint for failure to state a claim, see Fed.R.Civ.P. 12(b)(6). The district court granted the motion in part, dismissing Metropolitan Water’s § 113(f) contribution claim, but allowed the § 107(a) claim to go forward. We have jurisdiction over North American’s interlocutory appeal from this order, certified under 28 U.S.C. § 1292(b), and for the reasons set forth in the following opinion affirm the judgment of the district court.
I
BACKGROUND
A. Facts
In this appeal from the denial of a motion to dismiss, we accept as true all well-pleaded allegations in Metropolitan Water’s complaint and draw all reasonable inferences in its favor.
See Cler v. Illinois Educ. Ass’n,
These tanks, according to the complaint, were prone to leaks. Over the course of Lake River’s tenancy, the tanks allegedly spilled close to 12,000 gallons of industrial chemicals into the soil and groundwater. These toxins, the complaint further alleged, were “hazardous substances,” as that phrase is defined in CERCLA, see 42 U.S.C. § 9601(11), and posed an imminent danger to the environment. The complaint also stated that Metropolitan Water has “incurred substantial expenses” investigating, monitoring and remedying the contaminated portions of its property. R.9 at 6.
B. District Court Proceedings
In February 2003, Metropolitan Water filed this action against Lake River to recoup its costs in remedying the contamination. The original complaint asserted a claim under CERCLA § 107(a), see 42 U.S.C. § 9607(a), an alternative claim for contribution under CERCLA § 113(f), see *826 id. § 9613(f), and state law claims for nuisance and breach of contract. Lake River failed to answer the complaint, resulting in a default judgment that ordered Lake River to pay approximately $1.8 million in damages to Metropolitan Water, in addition to future response costs. Metropolitan Water then amended the complaint to add Lake River’s parent, North American, as a defendant; the amended complaint realleged the CERCLA counts and state law claims. North American then moved to dismiss under Federal Rule of Civil Procedure 12(b)(6).
In ruling on North American’s motion, the district court began by distinguishing the two CERCLA claims being asserted. The court first described § 107(a)’s liability provisions as providing an implied cause of action for cost recovery in cases “where a party is seeking direct recovery of costs incurred in cleaning up a hazardous waste site.” R.23 at 3. Section 113(f) claims for contribution, by contrast, are asserted by “potentially responsible parties,” or “PRPs,” seeking to apportion damages among themselves. The court recognized that Metropolitan Water, because it owned the property during the period of contamination, must be considered a PRP under CERCLA’s strict liability framework. Normally, the court noted, PRPs are limited to claims for contribution under § 113(f) and cannot recoup the full cost of remediation under the joint and several recovery of § 107(a). The court then observed that the Supreme Court had held recently in
Cooper Industries v. Aviall Services, Inc.,
After hearing oral argument from the parties, we invited the Environmental Protection Agency (“EPA”) to submit its views as amicus curiae. The EPA accepted our invitation, 1 and, with the permission of the court, Lockheed Martin Corporation also has submitted an amicus curiae brief. Both Metropolitan Water and North American now have filed supplemental briefs in response.
II
DISCUSSION
A.
1. CERCLA
In the 1970s and 80s, a number of high-profile environmental disasters, including the “Love Canal” dumping at Niagara Falls, New York, drew the public’s attention to the environmental risks and health hazards posed by improper hazardous waste disposal.
2
In response to rising public concern and the view that “existing law [was] clearly inadequate to deal with
*827
this massive problem,” H.R.Rep. No. 96-1016, pt. 1, at 22 (1980),
as reprinted in
1980 U.S.C.C.A.N 6119, 6120, Congress enacted the CERCLA. The law’s purpose was twofold. It was intended, for one, to “establish a comprehensive response and financing mechanism to abate and control the vast problems associated with abandoned and inactive hazardous waste disposal sites.” H.R.Rep. No. 96-1016, at 1. Second, CERCLA was meant to shift the costs of cleanup to the parties responsible for the contamination.
See Meghrig v. KFC Western, Inc.,
Enforcement of CERCLA rests primarily with the EPA, and the statute gives the agency a broad range of enforcement options. To implement the statute’s goals at a national level, the EPA is directed by CERCLA to formulate a National Contingency Plan outlining specific steps that parties must take in choosing a remedial action plan and in cleaning up hazardous waste.
See
40 C.F.R. pt. 300. In addition, for specific sites that the EPA deems an imminent threat, the agency is authorized to issue an administrative compliance order or obtain a court injunction, directing any responsible party to respond to the contamination.
See
42 U.S.C. § 9606(a). Additionally, if it chooses, the EPA may commence cleanup on its own using monies from the Hazardous Substances Superfund,
see id.
§ 9604, a fund established by CERLCA and financed through a combination of appropriations, EPA fees and industry taxes. 42 U.S.C. § 9605;
United States v. Hercules, Inc.,
After Superfund money has been spent by the EPA, CERCLA allows the agency to recover its costs from the responsible parties, who are divided by CERLCA § 107(a) into the following four statutory categories:
(1) the owner and operator of a vessel or a facility,
(2) any person who at the time of disposal of any hazardous substance owned or operated any facility at which such hazardous substances were disposed of,
(3) any person who by contract, agreement, or otherwise arranged for disposal or treatment, or arranged with a transporter for transport for disposal or treatment, of hazardous substances owned or possessed by such person, by any other party or entity, at any facility or incineration vessel owned or operated by another party or entity and containing such hazardous substances, and
(4) any person who accepts or accepted any hazardous' substances for transport to disposal or treatment facilities, incin-
eration vessels or sites selected by such person, from which there is a release, or a threatened release which causes the incurrence of response costs, of a hazardous substance....
42 U.S.C. § 9607. For these statutorily defined parties, or PRPs, liability under § 107(a) is strict, joint and several. In other words, by invoking § 107(a), the EPA may recover its costs in full from any responsible party, regardless of that party’s relative fault. 3
2. SARA
In the wake of CERCLA’s passage, an important question emerged: Whether a responsible party, who had been sued to commence cleanup or repay response costs, may obtain contribution from other responsible parties. As originally enacted
*828
in 1980, CERCLA did not provide expressly for a right of contribution.
See generally Cooper Indus.,
In 1986, Congress amended CERCLA by way of SARA to authorize expressly a contribution action. See SARA, Pub.L. No. 99 — 499, 100 Stat. 1613. The provision allowing for contribution states in relevant part: “Any person may seek contribution from any other person who is liable or potentially liable under section 9607(a) of this title, during or following any civil action under section 9606 of this title or under section 9607(a) of this title.” 42 U.S.C. § 9613(f)(1). In actions under this provision, the court allocates costs using equitable principles. Liability is several, as opposed to Section 107(a)’s joint and several scheme. In addition, SARA encourages parties to settle with the government by insulating any party that settles from being sued in a contribution action. See id. § 9613(f)(2).
SARA, in turn, produced its own set of new questions. Foremost was whether the new, codified right of contribution was now the only cause of action available to a PRP seeking to recover its cleanup costs. PRPs who had expended costs in remedying a site or settling liability understandably wished to seek joint and several cost recovery under § 107(a). Litigation ensued. Every circuit to decide the issue held that, after SARA, PRPs were precluded generally from seeking joint and several cost recovery under § 107(a), and that any claim seeking to shift costs from one responsible party to another must be brought as a § 113(f) claim for contribution.
4
These courts reasoned that a PRP, by definition, shares in some of the responsibility for the contamination. Therefore, any action by one PRP against another to equitably apportion liability is a “quintessential claim for contribution” and it would be unfair to allow a PRP to recover “100 percent of the response costs from others similarly situated.”
Bedford Affiliates v. Sills,
3. The Innocent Landowner Exception
CERCLA’s strict liability regime yields a great number of potentially liable individuals, in large part due to the practical reality that those truly responsible may not have the necessary money for the
*829
cleanup. For example, an absentee landowner may be liable under § 107(a) for the full cost of remedying a hazardous site caused by its tenant, even if the landowner had no reason to know that hazardous waste was being stored on its land.
5
To blunt the force of a rule that limits the rights of these “innocent” parties to contribution under § 113(f), our case law has developed what is known as the “innocent landowner” exception. Under the exception, which originated in
Akzo
and was reaffirmed in
Rumpke of Indiana, Inc. v. Cummins Engine Co., Inc.,
In Rumpke, the owner of a dump discovered, some six years after purchasing the site, that a “cocktail of hazardous wastes” had been deposited there regularly by a nearby recycling company. Id. at 1236. Recognizing that it now owned a veritable environmental disaster, the dump owner commenced voluntary cleanup and brought an action for both cost recovery under § 107(a) and for contribution under § 113(f)(1) against the company that had arranged the delivery of the toxins. Reversing an entry of summary judgment for the defendants, we decided that the dump owner, who was strictly liable but who had not actually contributed to the hazardous conditions, could maintain a direct cost recovery claim under § 107(a). In doing so, we emphasized that the dump owner had not been the subject of either governmental or private compulsion to initiate cleanup. It undertook cleanup on its own and, maintaining that it shared no actual responsibility for the site, was not trying to divide up its own liability or apportion costs. Therefore, we held that the claim was not one for contribution that had to be brought under § 113(f); a full cost recovery action remained available to the dump owner under § 107(a). 6
4. Cooper Industries, Inc. v. Aviall Services, Inc.
Recently, the Supreme Court had occasion to discuss the interplay between sections 107(a) and 113(f), and decided a key issue concerning the timing of a § 113(f) claim for contribution. In
Cooper Industries,
The Supreme Court held that § 113(f) did not authorize Aviall’s suit for contribution. The Court began by noting that the cost recovery remedy of § 107(a) and the contribution remedy of § 113(f)(1) are “clearly distinct.”
Id.
at 163
&
n. 3,
Notably, the Court did not rule out the availability of a § 107(a) action, observing in dictum that § 113(f)(1) is not the “exclusive cause of action for contribution available to a PRP.”
Cooper Indus.,
B.
We now must decide, in the wake of Cooper Industries, what rights of action, if any, are available to Metropolitan Water under CERCLA. It is clear, at the very least, that Metropolitan Water cannot bring suit under § 113(f) because it has not been the subject of an action for damages or compliance under CERCLA. 8 This conclusion, as the district court held, follows from a straightforward application of Cooper Industries. 9
Metropolitan Water and Lockheed urge us to hold, as the district court did, that a right of action exists under § 107(a) for private parties that, although potentially strictly liable for the costs of cleanup, have voluntary undertaken remediation and have no right to contribution under § 113(f)(1). They invite our attention first *831 to the statutory text of § 107(a), which they believe authorizes such a cause of action. The language- in focus provides that four statutorily defined categories of parties “shall be liable for” the government’s remedial and removal costs, see 42 U.S.C. § 9607(a)(4)(A), and for
(B) any other necessary costs of response incurred by any other person consistent with the national contingency plan;....
Id. § 9607(a)(4)(B). Metropolitan Water maintains that, under this provision’s plain wording, the only question is whether it is a “person” and whether it has incurred “necessary costs of response.” Id. Undoubtedly, as it points out, Metropolitan Water is a “person” within the meaning of CERCLA, which defines that term, inter alia, as a “firm” or “corporation.” Id. § 9601(21). Moreover, Metropolitan Water, as its complaint alleges, has incurred costs of response by taking “remedial action,” to “prevent or minimize the release of hazardous substances so that they do not migrate to cause substantial danger to present or future public health or welfare or the environment.” Id. § 9601(24). Thus, Metropolitan Water contends, § 107(a) makes its cost recovery remedy available; in very straightforward language, to any person that has incurred necessary costs of response, including PRPs.
North American responds that § 107(a)(4)(B) does nothing more than spell out the potential liability of responsible parties and does not create an authorization to sue. Although § 107(a)(4)(B) includes liability for the response costs of “any other person,” North American maintains that this language does not create a cause of action for “any other person,” particularly for PRPs such as Metropolitan Water.- The EPA agrees that Metropolitan Water has no cause of action under § 107(a), but interprets § 107(a)(4)(B) in a slightly - different manner. 'Unlike North American, the EPA acknowledges that the subsection creates a cause of action for some private parties. The agency, however, disagrees with Metropolitan Water about who specifically is. authorized to sue under the subsection. According to the EPA, the word “other” in the phrase “any other person” distinguishes those who may sue for cleanup costs from the four classes of potentially responsible parties listed earlier in subsections (1) through (4) of Section 107(a). 10 Thus, as the EPA-reasons, the phrase “any other person” refers to a class of individuals who by definition are not potentially responsible for cleanup costs. For parties like Metropolitan Water who are potentially liable for cleanup costs, the EPA submits, their only cause of action lies in the contribution provisions of § 113(f),-when available.
Relevant Supreme Court precedent compels us to reject, at the very least, the view taken by North American that § 107(a) does not create a cause of action at all. in
Key Tronic Corp. v. United States,
The Supreme Court accepted certiorari only to decide whether § 107(a) authorized Key Tronic to recover its attorneys fees. Although the Court held ultimately that attorneys fees were unavailable, it also undertook a comprehensive discussion of the rights of action available under CERC-LA. The Court began with the premise that “ § 107 unquestionably provides a cause of action for private parties to seek recovery of cleanup costs.”
Id.
át 818,
The Court’s discussion in
Key Tronic
therefore dismisses any notion that § 107(a) does not authorize at least some parties to sue. Moreover, in
Cooper Industries,
the Court reaffirmed
Key Tronic’s
recognition of a “cost recovery remedy of § 107(a)(4)(B)” that is “clearly distinct” from the contribution remedy in Section 113(f)(1).
Cooper Indus.,
C.
Despite recognizing an implied cause
oí
action under § 107(a), however, these cases appear to leave open the question we now face of whether § 107(a) authorizes a cause of action by potentially liable parties in Metropolitan Water’s situation.
11
This precise question has been addressed by three federal courts of appeals in the aftermath of
Cooper
Industries.
12
In
Consoli
*833
dated, Edison Co. of New York, Inc. v. UGI Utilities, Inc.,
Turning first to the decision of the Second Circuit, Consolidated Edison sought reimbursement from the operator of one of its power plants for cleanup costs that Consolidated Edison had incurred in remedying hazardous waste contamination. Consolidated Edison’s complaint asserted claims under both § 107(a) and § 113(f). The court held first that a § 113(f) claim for contribution was unavailable under these circumstances because Consolidated Edison had not been sued under CERCLA or resolved CERCLA liability through settlement.
Instead, the court held, Consolidated Edison was entitled to pursue its action under § 107(a). After reviewing the statutory scheme and the effect of the Supreme Court’s decision in
Cooper Industries,
the Second Circuit concluded that sections 107(a) and 113(f) each “embod[y] a mechanism for cost recovery available to persons in different procedural circumstances.”
Consol. Edison,
Like the Second Circuit, the Eighth Circuit in
Atlantic Research
was faced with the following question: “Can one liable party recover costs advanced, beyond its equitable share, from another liable party in direct recovery, or by § 107 contribution, or as a matter of federal common law?”
The Court of Appeals for the Third Circuit, however, reached a conclusion different from that of the Second and Eighth Circuits. In
E.I. DuPont,
the company-plaintiff owned property which “was owned or operated by the United States at various times during World War I, World War II, and/or the Korean War, during which time the United States was responsible for some contamination.”
E.I DuPont De Nemours,
After reviewing the rationales of our sister circuits, we find ourselves in agreement with the conclusion reached by the Second and Eighth Circuits, and by Judge Sloviter in her dissenting opinion in E.I. DuPont. The Supreme Court’s continued recognition of an implied cause of action in § 107(a), coupled with that subsection’s plain language, convince us that Metropoli *835 tan Water may sue under § 107(a) to recover necessary response costs.
Section 107(a) states in relevant part that a responsible party
(4) ••• shall be liable for—
(A) all costs of removal or remedial action incurred by the United States Government or a State or an Indian tribe not inconsistent with the national contingency plan;
(B) any other necessary costs of response incurred by any other person consistent with the national contingency plan;. ...
42 U.S.C. § 9607(a)(4). Nothing in subsection (B) indicates that a potentially liable party, such as Metropolitan Water, should not be considered “any other person” for purposes of a right of action.
Certainly, as the EPA points out, the word “other” in that phrase should be given meaning as a distinguishing term. Yet, we disagree that the word “other” distinguishes “any other person” from the four categories of potentially responsible parties listed earlier in subsections (1) through (4) of § 107(a). Rather, we read “other” as distinguishing “any other person” from the “United States Government,” a “State” or an “Indian tribe,” the parties listed in the immediately preceding subsection. Id. These parties, as subsection (A) states, may recover costs “not inconsistent with the national contingency plan.” Id. § 9607(a)(4)(A) (emphasis added). By contrast, “any other person” is limited to recovery of those costs “consistent with the national contingency plan.” Id. § 9607(a)(4)(B) (emphasis added). Thus, we read the two subsections, and the reference to “any other person,” simply as the statute’s way of relaxing the burden of proof for governmental entities as opposed to private parties. 16
The only remaining questions, then, under § 107(a) are whether Metropolitan Water is a “person” and whether it has incurred “necessary costs of response.” Id. § 9607(a)(4)(B). Without question, Metropolitan is a “person” under CERC-LA because it is a “firm” or a “corporation” within the meaning of the act. Id. § 9601(21). Moreover, the complaint in the present case alleges that Metropolitan Water incurred “ ‘response’ costs within the meaning of § 101(25) of CERCLA (42 U.S.C. § 9601(25)) including investigation, monitoring and clean-up costs.” R.17 at 14. Finally, the allegations in the complaint make clear that Metropolitan Water neither has settled any liability with a government entity nor has been the subject of a CERCLA suit for damages. These allegations adequately plead a cause of action under § 107(a).
Recognizing in § 107(a) a right of action for Metropolitan Water also appears in line with the explicit savings clause found in § 113(f)(1). The last sentence of § 113(f)(1) provides: “Nothing in this subsection shall diminish the right of any person to bring an action for contribution in the absence of, a civil action under [§ 106] of this title or [§ 107] of this title.” 42 U.S.C. § 9613(f)(1). As the Supreme Court stated in
Cooper Industries,
“the
*836
sentence rebuts any presumption that the express right of contribution provided by the enabling clause [of § 113(f) ] is the exclusive cause of action for contribution available to a PRP.”
Cooper Indus.,
Our holding today does not require us to revisit our
pre-Cooper Industries
decision in
Akzo Coatings,
in which we held that a claim “by and between jointly and severally liable parties for an appropriate division of the payment one of them has been compelled to make” must be brought under § 113(f)(1).
Akzo Coatings,
In addition, we are concerned that prohibiting suit by a voluntary plaintiff like Metropolitan Water may undermine CERCLA’s twin aims of encouraging expeditious, voluntary environmental cleanups while holding responsible parties accountable for the response costs that their past activities induced. As
Consolidated Edison, Atlantic Research
and several post-Cooper
Industries
district court decisions have recognized, in order to further CERCLA’s policies, potentially responsible parties must be allowed to recover response costs even before they have been sued themselves under CERCLA or have settled their CERCLA liability with a government entity. Were a cost recovery action unavailable in these circumstances, the Second Circuit reasoned, “such parties would likely wait until they are sued to commence cleaning up any site for which they are not exclusively responsible because of their inability to be reimbursed for cleanup expenditures in the absence of a suit.”
Consol. Edison,
North American and the EPA respond to this policy argument with one of their own. They contend that the United States may lose valuable settlement leverage if parties such as Metropolitan Water are allowed to bring an action under § 107(a) in these circumstances. They point out that PRPs who choose to settle with the United States enjoy protection from contribution suits by other parties and retain the ability to seek contribution themselves. See 42 *837 U.S.C. § 9613(f)(2). By contrast, PRPs who choose not to settle are barred from seeking contribution under § 113(f) from the settling parties and thus face potentially disproportionate liability. If the statute were to allow non-settling parties to sue under § 107(a), even when unable to do so under § 113(f), North American and the EPA contend that PRPs would be discouraged from settling with the United States.
We are sensitive to the EPA’s concerns regarding diminished settlement leverage. Certainly, the contribution protection provision in § 113(f)(2) appears to reflect a congressional desire that PRPs ought to be encouraged to settle their liability with the United States. However, these concerns simply do not exist in the circumstances presented here. In this case, the allegations of the complaint make clear that neither the EPA nor any other government entity has involved itself in the cleanup undertaken by Metropolitan Water. As far as the complaint indicates, Metropolitan Water’s undertaking was completely voluntary and financed by Metropolitan Water alone. In the present case, the EPA simply is not in the picture and has no reason to purse a settlement.
We hold that Metropolitan Water has a right of action under CERCLA § 107(a). 18
Conclusion
For the foregoing reasons, the judgment of the district court is affirmed.
Affirmed
Notes
. The court expresses its thanks to the EPA for its valuable assistance.
. For details on the Love Canal site, see A. Theodore Steegmann, Jr., History of Love Canal and SUNY at Buffalo’s Response: History, The University Role, and Health Research, 8 Buff Envtl. L.J 173 (2001).
. The only exception to joint liability is when the harm is divisible, but this is a rare scenario.
.
See Morrison Enters. v. McShares, Inc.,
. Section 107(b) provides a limited set of affirmative defenses for parties who would otherwise be strictly liable. The defenses require showing that the damage was caused by (1) "an act of God;” (2) "an act of war;” or (3) an act of a third party who has no contractual privity to the defendant. Metropolitan Water has not pleaded any of these affirmative defenses.
. We imagined in
Rumpke
that "one of two outcomes would follow from a landowner suit under § 107(a): either the facts would establish that the landowner was truly blameless, in which case the other PRPs would be entitled to bring a suit under § 113(f) ..., or the facts would show that the landowner was also partially responsible, in which case it would not be entitled to recover under its § 107(a) theory and only the § 113(f) claim would go forward.”
Rumpke of Indiana, Inc. v. Cummins Engine Co., Inc.,
.Justice Ginsburg in dissent, joined by Justice Stevens, argued that Aviall, despite being a PRP, retained a cause of action under § 107(a) to recover a proportionate share of its cleanup costs. In the dissent's view, the Court should have reached this issue, even though Aviall brought its action ostensibly under § 113(f). According to the dissent, Aviall’s reliance on § 113(f) instead of 107(a) was simply an effort to "conform! 1 its pleading to then-governing Fifth Circuit precedent, which held that a CERCLA contribution action arises through the joint operation of § 107(a) and § 113(f)(1).”
Cooper Indus., Inc. v. Aviall Servs., Inc.,
. Indeed, as far as the limited record indicates, Metropolitan Water has not come under any governmental scrutiny whatsoever.
. Remarkably, Metropolitan Water refuses to concede that its § 113(f) contribution claim is barred by
Cooper Industries.
We must reject this contention because the Supreme Court could not have been clearer when it said: "The issue we must decide is whether a private party who has not been sued under § 106 or § 107(a) may nevertheless obtain contribution under § 113(f)(1) from other liable parties. We hold that it may not.”
Cooper Indus.,
. As discussed earlier, § 107(a) enumerates four classes of potentially responsible parties: (1) owners of facilities with hazardous substances; (2) former owners of facilities with hazardous substances; (3) generators of hazardous ■ substances; and (4) transporters of hazardous substances. 42 U.S.C. § 9607(a)(l)-(4).
. We recognize that the plaintiff in Key Tronic was, just like Metropolitan Water, a potentially responsible party who brought suit under Section 107(a). However, the issue before the Court in Key Tronic was attorneys’ fees, not the availability of a right of action under Section 107(a). We therefore cannot read Key Tronic’s discussion as anything more than the tacit approval of a PRP's right of action in these circumstances.
. Since
Cooper Industries,
a number of district courts have held that a PRP, who cannot seek recovery under section 113(f), may nonetheless bring a cause of action under section 107(a).
See Raytheon Aircraft Co. v. United States,
. Judge Sloviter filed a dissenting opinion.
. The Eighth Circuit went on to conclude that "the broad language of § 107 supports not only a right of cost recovery but also an implied right to contribution.”
Atl. Research Corp. v. United States,
. In her dissenting opinion, Judge Sloviter disagreed with the majority's conclusion that
Cooper Industries
did not "weaken[ ] the conceptual underpinnings” of the court’s prior case law.
E.I. DuPont De Nemours & Co. v. United States,
. Indeed, other circuits have understood this portion of the statute as distinguishing between the Government's burden of proof and that of private citizens. In
United States
v.
E.I. DuPont De Nemours & Co.,
. For this reason, we hesitate to label Metropolitan Water's right of action under § 107 an “implied right to contribution,” as the district court did. Under the technical definition of contribution at common law, a volunteer who is not itself liable may not pursue contribution. See 18 Am.Jur.2d Contribution § 15; Restatement (Second) of Torts § 886A(1) & cmts. b & e. Section 107(a) only imposes liability on private parties to the extent there have been "necessary costs of response” already incurred. 42 U.S.C. § 9607(a)(4). If no costs qualifying under this language have been incurred or awarded against the volunteer, then that party has no right to contribution. When Metropolitan Water commenced cleanup, no other party had taken remedial action and there was no common liability. Therefore, Metropolitan Water's action under § 107 is characterized more appropriately as a cost-recovery action than as a claim for contribution.
. In reaching this holding, we find it unnecessary to decide whether Metropolitan Water falls within the "innocent landowner” exception recognized by some of our
pre-Cooper Industries
decisions.
See, e.g., Rumpke,