In two major Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) opinions, United States v. Atlantic Research, Inc. and Burlington Northern & Santa Fe R.R. v. United States, the U.S. Supreme Court provided long-sought guidance for parties litigating hazardous waste cleanup issues under CERCLA. Atlantic Research addressed the right of certain potentially responsible parties (PRPs) under CERCLA--those who had incurred CERCLA response costs without being subject to prior litigation or administrative action--to bring a §107 cost recovery action against other allegedly liable parties. This issue became critical when the Court's 2004 Cooper Industries, Inc. v. Aviall Services, Inc. decision held that such a party could not assert a §113 contribution claim, the usual remedy in such cases. Burlington Northern addressed the standards that would govern "divisibility" of a CERCLA site--one mechanism by which parties can avoid joint and several liability--as well as the standards for "arranger liability" under CERCLA in the context of sales of a useful product. Burlington Northern has widely been recognized as a setback for the aggressive theories of joint and several liability often advanced by the government in CERCLA enforcement actions, although the full implications of the decision are not yet clear. At minimum, Burlington Northern reiterated traditional principles of common-law apportionment and reduced--but definitely did not eliminate--the prospects for joint and several liability to be imposed on parties at a CERCLA site.

This Article addresses some of the major issues that remain open after Atlantic Research and Burlington Northern. First, does Atlantic Research allow all PRPs to assert §107 cost recovery claims against other PRPs, or only some limited category of PRPs? Second, are PRPs asserting §107 claims entitled to obtain joint and several liability against other PRPs? And how does this affect the government at sites where it is also a PRP? Third, does the contribution protection provided to settling parties under CERCLA protect them from §107 claims? Fourth, what are the operative standards for establishing divisibility at a CERCLA site post-Burlington Northern? Fifth, can the government avoid limitations on joint and several liability by showing that a PRP's individual contribution would have required the same remedy if there had been no other PRPs involved? Last, to what extent do limitations on joint and several liability and a reinvigorated divisibility defense impact the government's ability to impose unilateral administrative orders under §106 of CERCLA?