What are the four categories of potentially responsible party under CERCLA?
The Comprehensive Environmental Response, Compensation, and Liability Act names four categories of potentially responsible party at 42 U.S.C. § 9607(a), and a party fitting any one of them can be held liable for the full cost of cleaning up a site. The first category is “the owner and operator of a vessel or a facility” — whoever owns or operates the property today, regardless of whether that owner had anything to do with the contamination. The second is 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” — a past owner or operator, reaching back to whoever held the property when the hazardous substance was actually disposed of there.
The third category is the arranger: any person who, “by contract, agreement, or otherwise arranged for disposal or treatment” of hazardous substances that it owned or possessed, at a facility owned or operated by another party. The fourth is the transporter: any person who accepted hazardous substances for transport to a disposal or treatment facility and who selected that facility. All four categories are set out in the same subsection, 42 U.S.C. § 9607(a), read in full at Cornell Law School's Legal Information Institute. None of the four categories asks whether the party intended to contaminate anything, and none excuses a party for having complied with the law in effect at the time it acted — liability under this section does not turn on fault.
The costs a covered person can be made to pay are also listed in the same section: “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,” “any other necessary costs of response incurred by any other person consistent with the national contingency plan,” and damages for injury to natural resources, among other categories. Whether a particular party actually fits one of the four categories on a given set of facts, and what its equitable share should be relative to other responsible parties, are both questions this Institute connects to the right technical and legal expertise rather than answers here — the framework is covered further at CERCLA Liability, Cost Recovery & Allocation.
Is CERCLA liability strict, and can one responsible party be made to pay the whole cleanup?
Yes. Liability under 42 U.S.C. § 9607(a) is strict, meaning a covered person can be held liable without any showing of negligence or intent, and courts have long read the statute, together with its legislative history, as imposing joint and several liability on multiple responsible parties where the resulting environmental harm is a single, indivisible one. Joint and several liability means the government or a private cost-recovery plaintiff is not required to sue every contributing party or to prove each one's individual share before recovering — it can pursue the full cost of cleanup from whichever responsible party is easiest to collect from, leaving that party to seek reimbursement from the others.
That default is not absolute, and the Supreme Court addressed its limit directly in Burlington Northern & Santa Fe Railway Co. v. United States, 556 U.S. 599 (2009). The Court applied the rule stated in the Restatement (Second) of Torts § 433A: “when two or more persons acting independently caus[e] a distinct or single harm for which there is a reasonable basis for division according to the contribution of each, each is subject to liability only for the portion of the total harm that he has himself caused.” The burden of proving that a reasonable basis for apportionment exists falls on the defendant seeking to avoid joint and several liability, not on the plaintiff.
On the facts before it in Burlington Northern, the district court had apportioned only 9 percent of the total response cost to the railroad defendants, calculating that figure, as the Supreme Court described it, from three numbers: the percentage of the total area of the facility the railroads owned, the duration of the lessee's business divided by the term of the railroads' lease, and a finding that only two of the polluting chemicals spilled on the leased parcel required remediation and that those chemicals accounted for roughly two-thirds of the remediable site contamination. The Supreme Court held that the District Court “reasonably apportioned the Railroads' share of the site remediation costs at 9%.” What Burlington Northern establishes is the availability of apportionment in principle and the standard that governs it, not a formula that transfers to a different site's facts; whether a reasonable basis for apportionment exists on any given record is decided case by case.
What is the difference between a cost recovery claim and a contribution claim under CERCLA?
A cost recovery claim under 42 U.S.C. § 9607(a) and a contribution claim under 42 U.S.C. § 9613(f) both let a party that paid for cleanup recover money from other responsible parties, but they are available in different circumstances and the Supreme Court has held they are not interchangeable. Section 9613(f)(1) provides that “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 or section 9607(a) — contribution is expressly tied to that litigation posture.
The Supreme Court read that condition as a limit rather than an example in Cooper Industries, Inc. v. Aviall Services, Inc., 543 U.S. 157 (2004). Aviall had cleaned up sites under pressure from a Texas state agency, without ever being sued under section 9606 or section 9607(a), and then sought contribution from Cooper Industries under section 9613(f)(1). The Court held that section 9613(f)(1) does not authorize a contribution claim brought by a party that has not been sued under section 9606 or section 9607(a) — the “during or following” language in the statute states a condition on when a contribution claim exists, and a party outside that condition cannot use the section.
Cooper Industries left open what remedy, if any, existed for a party in Aviall's position — one that voluntarily incurred its own cleanup costs without being sued. The Court answered that question in United States v. Atlantic Research Corp., 551 U.S. 128 (2007), holding that 42 U.S.C. § 9607(a)(4)(B), which allows recovery of “any other necessary costs of response incurred by any other person,” gives a potentially responsible party that has itself incurred cleanup costs its own cause of action against other responsible parties, separate from contribution under section 9613(f). The practical effect of the two decisions together is that which route is open — cost recovery under section 9607(a) or contribution under section 9613(f) — depends on whether the party seeking reimbursement was sued or acted voluntarily, and on how it incurred its own costs in the first place; getting that characterization right is frequently the subject of its own litigation.
Can a landowner who did not cause the contamination avoid CERCLA liability?
CERCLA gives a landowner who did not cause the contamination three distinct routes out of liability, and all three share one structural requirement: an investigation of the property's environmental condition, called all appropriate inquiries, carried out at or before acquisition. Two of the three additionally require that the disposal happened before that person acquired the property; the third, the contiguous property owner provision, does not, because the contamination it deals with comes from land the person does not own. The first is the innocent landowner defense, built on the definition of “contractual relationship” at 42 U.S.C. § 9601(35). It applies where the real property was “acquired by the defendant after the disposal or placement of the hazardous substance on, in, or at the facility” and the defendant “did not know and had no reason to know that any hazardous substance which is the subject of the release or threatened release was disposed of on, in, or at the facility.” Establishing “no reason to know” requires the defendant to have carried out what the statute calls all appropriate inquiries into the property's previous ownership and uses before buying it, consistent with generally accepted commercial practice.
The second route is the bona fide prospective purchaser status defined at 42 U.S.C. § 9601(40), added to the statute for purchasers who acquire ownership of a facility “after January 11, 2002” (42 U.S.C. § 9601(40)(A)(i)(I)) and who may, unlike an innocent landowner, actually know about the contamination going in. The first of its listed criteria is the same threshold requirement: “All disposal of hazardous substances at the facility occurred before the person acquired the facility.” A bona fide prospective purchaser must also establish the remaining criteria in the statute by a preponderance of the evidence, including cooperating with response actions, complying with land use controls, and not impeding the effectiveness of institutional controls placed on the site.
The third route, the contiguous property owner provision at 42 U.S.C. § 9607(q), is not framed as a defense at all — a qualifying person “shall not be considered to be an owner or operator” under section 9607(a)(1) or (2) solely by reason of the contamination — and it is built for a different situation — a person who owns property next to, rather than on top of, the contamination, onto which hazardous substances migrated from a neighboring source. That person can avoid being treated as an owner or operator by showing, among other things, that they “did not cause, contribute, or consent to the release,” that they are not affiliated with a liable party, and that they conducted all appropriate inquiry within the meaning of 42 U.S.C. § 9601(35)(B) and did not know or have reason to know the property was or could be contaminated when they acquired it. All three defenses can be lost — a party that fails to take reasonable steps once contamination is discovered, or that obstructs response personnel, forfeits the protection regardless of how clean its acquisition was.
What is the all appropriate inquiries requirement, and why does it matter for these defenses?
All appropriate inquiries is the pre-purchase investigation into a property's environmental condition and history that CERCLA requires before a buyer can claim the innocent landowner defense, bona fide prospective purchaser status, or the contiguous property owner exclusion — each of the three defenses covered above depends on having done it, and a purchaser who skips it forfeits all three regardless of what the investigation would have found. EPA's implementing regulation is codified at 40 C.F.R. Part 312. It sets out its own requirements for the inquiry at 40 C.F.R. §§ 312.20 through 312.31 — including that all appropriate inquiries “must be conducted within one year prior to the date of acquisition of the subject property,” with interviews, lien searches, government records reviews and the visual inspection conducted or updated within 180 days of and prior to acquisition (40 C.F.R. § 312.20) — and separately lists, at 40 C.F.R. § 312.11, industry standards that “may be used to comply with the requirements set forth in §§ 312.23 through 312.31.” Following the regulation directly and using a listed ASTM standard are alternative routes, not the same route.
The standard listed for ordinary commercial property is ASTM International's E1527-21, “Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process” (40 C.F.R. § 312.11(a)); a separate standard, ASTM E2247-23, is listed for forestland and rural property (40 C.F.R. § 312.11(b)). EPA added the E1527-21 reference in a final rule published at 87 Fed. Reg. 76578 on December 15, 2022, effective February 13, 2023, which by its own summary amended the rule to reference E1527-21 “and to remove after one year recognition of the previous version of that standard, ASTM E1527-13, as compliant with the AAI rule.” That sunset is written into the regulation itself: 40 C.F.R. § 312.11(c) recognizes E1527-13 only “[u]ntil February 13, 2024.” EPA added in the same rulemaking that “[a] Phase 1 Environmental Site Assessment completed before that date using ASTM E1527-13 will be recognized as compliant with the All Appropriate Inquiries Rule.” A Phase I assessment is not itself a defense in any event; it is evidence offered to prove the “no reason to know” element that the landowner protections require, and it has to be current enough and thorough enough to support that element on the facts of the acquisition.
How do state cleanup programs differ from cleanup under CERCLA?
State cleanup programs operate alongside CERCLA rather than as a substitute for it, and a completion certificate issued under a state program does not automatically extinguish liability under the federal statute. Many states run some form of voluntary cleanup program, under which a party agrees to investigate and remediate a site in exchange for a measure of protection from that state's own future enforcement. The programs vary considerably in scope and in what protection they actually confer, so the terms of the specific state's program, not an assumption drawn from CERCLA, control.
Texas's program illustrates both the appeal and the limit. The Texas Commission on Environmental Quality describes its Voluntary Cleanup Program as “a brownfields program designed to address sites that are burdened by real or reasonably perceived environmental issues that may hamper real estate transactions or redevelopment,” and says that “all non-responsible parties, including future lenders and landowners, receive protection from liability to the state of Texas for cleanup of sites under the VCP.” Once a site meets the applicable remedy standard, TCEQ issues a Certificate of Completion “which states that all non-responsible parties are released from all liability to the state for cleanup of areas covered by the certificate.” Read the qualifier: the release is addressed to non-responsible parties. A party the agency does treat as responsible does not obtain it by participating.
The other phrase to read carefully is “liability to the state.” A release issued under a state program addresses that state's own enforcement authority; it does not by itself bind EPA or foreclose federal liability under CERCLA, and it does not resolve a private cost-recovery or contribution claim brought by another responsible party under section 9607(a) or section 9613(f). Whether a given state's completion certificate carries any weight in a federal or private action, and what a specific state's program requires to qualify, are questions this Institute does not answer in the abstract — they turn on the law of the state and the posture of the matter, and are best worked through with counsel who practices in that state.