Karen Silkwood, a laboratory analyst at Kerr-McGee's Cimarron, Oklahoma, nuclear plant, was contaminated by plutonium at the work site. On November 13, 1974, eight days after the contamination was first detected, Karen was killed in an automobile accident. Her father, Bill Silkwood, as administrator of Karen's estate, brought a diversity of citizenship action in a federal district court, seeking to recover damages for injuries resulting from the plutonium contamination. This lawsuit was based on common law tort principles embodied in Oklahoma law. The jury decided in Silkwood=s favor, awarding $505,000 in compensatory damages and $10 million in punitive damages. The Court of Appeals for the Tenth Circuit reversed, holding, among other things, the punitive damages award was preempted by federal law. The Supreme Court granted Silkwood's petition for certiorari.

Justice White delivered the opinion of the Court.

... As we recently observed in Pacific Gas & Electric Co. v. State Energy Resources Conservation & Development Comm=n, *** state law can be preempted in either of two general ways. If Congress evidences an intent to occupy a given field, any state law falling within that field is pre-empted. *** Even where Congress has not entirely displaced state regulation in the field in question, state law is still preempted to the extent it actually conflicts with federal law, that is, when it is impossible to comply with both state and federal law, *** or where the state law stands as an obstacle to the accomplishment of the full purposes and objectives of Congress. ** Kerr-McGee contends that the award in this case is invalid under either analysis. We consider each of the contentions in turn....

Kerr-McGee argues that our ruling in Pacific Gas & Electric is dispositive of the issue in this case. Kerr-McGee submits that because the state-authorized award of punitive damages in this case punishes and deters conduct related to radiation hazards, it falls within the prohibited field. However, a review of the same legislative history which prompted our holding in Pacific Gas & Electric, coupled with an examination of Congress' actions with respect to other portions of the Atomic Energy Act, convinces us that the pre-empted field does not extend as far as Kerr-McGee would have it....

... If there were nothing more, this concern over the States' inability to formulate effective standards and the foreclosure of the States from conditioning the operation of nuclear plants on compliance with state-imposed safety standards arguably would disallow resort to state-law remedies by those suffering injuries from radiation in a nuclear plant. There is, however, ample evidence that Congress had no intention of forbidding the States to provide such remedies.

Indeed, there is no indication that Congress even seriously considered precluding the use of such remedies either when it enacted the Atomic Energy Act in 1954 or when it amended it in 1959. This silence takes on added significance in light of Congress' failure to provide any federal remedy for persons injured by such conduct. It is difficult to believe that Congress would, without comment, remove all means of judicial recourse for those injured by illegal conduct. ***

More importantly, the only congressional discussion concerning the relationship between the Atomic Energy Act and state tort remedies indicates that Congress assumed that such remedies would be available. After the 1954 law was enacted, private companies contemplating entry into the nuclear industry expressed concern over potentially bankrupting state-law suits arising out of a nuclear incident. As a result, in 1957 Congress passed the Price-Anderson Act, an amendment to the Atomic Energy Act. *** That Act established an indemnification scheme under which operators of licensed nuclear facilities could be required to obtain up to $60 million in private financial protection against such suits. The Government would then provide indemnification for the next $500 million of liability, and the resulting $560 million would be the limit of liability for any one nuclear incident.

Although the Price-Anderson Act does not apply to the present situation, the discussion preceding its enactment and subsequent amendment indicates that Congress assumed that persons injured by nuclear accidents were free to utilize existing state tort law remedies.

Congress clearly began working on the Price-Anderson legislation with the assumption that in the absence of some subsequent legislative action, state tort law would apply This was true even though Congress was fully aware of the exclusive regulatory authority over safety matters.

When it enacted the Price-Anderson Act, Congress was well aware of the need for effective national safety regulation. In fact, it intended to encourage such regulation. But, at the same time, "the right of the State courts to establish the liability of the persons involved in the normal way [was] maintained.***

The belief that the NRC's (Nuclear Regulatory Commission] exclusive authority to set safety standards did not foreclose the use of state tort remedies was reaffirmed when the Price-Anderson Act was amended in 1966. The 1966 amendment was designed to respond to concerns about the adequacy of state-law remedies. *** It provided that in the event of an "extraordinary nuclear occurrence," licensees could be required to waive any issue of fault, any charitable or governmental immunity defense, and any statute of limitations defense of less than 10 years. *** Again, however, the importance of the legislation for present purposes is not so much in its substance, as in the assumptions on which it was based. .. ."Absent ... a determination [that the incident is an "extraordinary nuclear occurrence"], a claimant would have exactly the same rights that he has today under existing law - including, perhaps, benefit of a rule of strict liability if applicable State law so provides." *** Indeed, the entire discussion surrounding the 1966 amendment was premised on the assumption that state remedies were available notwithstanding the NRC's exclusive regulatory authority...

Kerr-McGee focuses on the differences between compensatory and punitive damages awards and asserts that, at most, Congress intended to allow the former. This argument, however, is misdirected because our inquiry is not whether Congress expressly allowed punitive damages awards. Punitive damages have long been a part of traditional principles of state tort law would apply with full force unless they were expressly supplanted. Thus, it is Kerr-McGee=s burden to show that Congress intended to preclude such awards. *** Yet, the company is unable to point to anything in the legislative history or in the regulations that indicates that punitive damages were not to be allowed. To the contrary, the regulations issued implementing the insurance provisions of the Price-Anderson Act themselves contemplate that punitive damages might be awarded under state law.

In sum, it is clear that in enacting and amending the Price-Anderson Act, Congress assumed that state-law remedies, in whatever form they might take, were available to those injured by nuclear incidents. This was so even though it was well aware of the NRC's exclusive authority to regulate safety matters.

No doubt there is tension between the conclusion that safety regulation is the exclusive concern of the federal law and the conclusion that a State may nevertheless award damages based on its own law of liability. But as we understand what was done over the years in the legislation concerning nuclear energy, Congress intended to stand by both concepts and to tolerate whatever tension there was between them. We can do no less. It may be that the award of damages based on the state law of negligence or strict liability is regulatory in the sense that a nuclear plant will be threatened with damages liability if it does not conform to state standards, but that regulatory consequence was something that Congress was quite willing to accept.

We do not suggest that there could never be an instance in which the federal law would pre-empt the recovery of damages based on state law. But insofar as damages for radiation injuries are concerned, preemption should not be judged on the basis that the Federal Government has so completely occupied the field of safety that state remedies are foreclosed but on whether there is an irreconcilable conflict between the federal and state standards or whether the imposition of a state standard in a damages action would frustrate the objectives of the federal law. We perceive no such conflict or frustration in the circumstances of this case.

The United States, as amicus curiae, contends that the award of punitive damages in this case is pre-empted because it conflicts with the federal remedial scheme, noting that the NRC is authorized to impose civil penalties on licensees when federal standards have been violated. *** However, the award of punitive damages in the present case does not conflict with that scheme. Paying both federal fines and state-imposed punitive damages for the same incident would not appear to be physically impossible. Nor does exposure to punitive damages frustrate any purpose of the federal remedial scheme.

Kerr-McGee contends that the award is pre-empted because it frustrates Congress' express desire "to encourage widespread participation in the development and utilization of atomic energy for peaceful purposes." [However] Congress ... disclaimed any interest in promoting the development and utilization of atomic energy by means that fail to provide adequate remedies for those who are inured by exposure to hazardous nuclear materials.

We also reject Kerr-McGee's submission that the punitive damages award in this case conflicts with Congress' express intent to preclude dual regulation of radiation hazards. Congress did not believe that it was inconsistent to vest the NRC with exclusive regulatory authority over the safety aspects of nuclear development while at the same time allowing plaintiffs like Silkwood to recover for injuries caused by nuclear hazards. We are not authorized to second-guess that conclusion.

We conclude that the award of punitive damages in this case is not pre-empted by federal law. The judgment of the Court of Appeals with respect to punitive damages is therefore reversed, and the case is remanded to that court for proceedings consistent with this opinion.

It is so ordered.

Justice Blackmun, with whom Justice Marshall joins, dissenting.

I join Justice Powell's opinion in dissent and add comments of my own that, I believe, demonstrate (a) the incompatibility between the Court's opinion last Term in Pacific Gas & Electric Co. v State Energy Resources Conservation & Development Comm=n*** (1983), and its opinion in the present case, and (b) the fact that the Court is by no means compelled to reach the result it espouses today.

Justice Powell's dissent well explains the fundamental incongruity of the Court's result. The Court acknowledges that Congress pre-empted state regulation of safety aspects of nuclear operations largely out of concern that States were without the technological expertise necessary to regulate them. Yet the Court concludes that Congress intended to allow a jury to impose substantial penalties upon a nuclear licensee for failure to follow what the jury regards as adequate safety procedures. The Court recognizes the paradox of its disposition, but blames the irrationality on Congress. Then, with humility, the Court explains that it is duty-bound to follow the dictates of Congress. But such institutional modesty cannot transfer the blame for the tension that today's decision injects into the regulation of nuclear power. The Court, in my view, tortures its earlier decisions and, more importantly, wreaks havoc with the regulatory structure that Congress carefully created....

Justice Powell, with whom the Chief Justice and Justice Blackmun join, dissenting.

The Court's decision, in effect, authorizes lay juries and judges in each of the States to make regulatory judgments as to whether a federally licensed nuclear facility is being operated safely. Such judgments then become the predicate to imposing heavy punitive damages. This authority is approved in this case even though the Nuclear Regulatory Commission (NRC) (then the Atomic Energy Commission [AEC]) - the agency authorized by Congress to assure the safety of nuclear facilities - found no relevant violation of its stringent safety requirements worthy of punishment. The decision today also comes less than a year after we explicitly held that federal law has "pre-empted" all "state safety regulation" except certain limited powers "expressly ceded to the States." There is no express authorization in federal law of the authority the Court today finds in a state's common law of torts.

Punitive damages, unrelated to compensation for any injury or damage sustained by a plaintiff, are "regulatory" in nature rather than compensatory. The Court of Appeals for the Tenth Circuit so found in this case - prior even to our decision in Pacific Gas & Electric Co. *** It also concluded that punitive damages are "no less intrusive than direct legislative acts of the state." *** I agree with the Court of Appeals....

In sum, the Court's decision will leave this area of the law in disarray. No longer can the operators of nuclear facilities rely on the regulations and oversight of the NRC. Juries unfamiliar with nuclear technology may be competent to determine and assess compensatory damages on the basis of liability without fault. They are unlikely, however, to have even the most rudimentary comprehension of what reasonably must be done to assure the safety of employees and the public. The District Court, in this case, by instructing the jury that it could infer malice, fraud, or gross negligence (see ibid.), in effect authorized the jury to impose punitive damages without fault. And, to make sure that the jury understood its standardless freedom in this respect, the Court also instructed the jury that it could ignore the regulations prescribed by the AEC if in its opinion they defied "human credence" or "can be shown not to accomplish their intended purpose." ***

We hardly could have spoken more clearly in Pacific Gas & Electric Co. on April 20, 1983, on the issue of preemption.... This left no doubt whatever as to the sole responsibility for nuclear safety regulation under the governance of the NRC and its large staff - experts in the technology and safety controls of nuclear energy. This case makes clear the correctness of the Court's holding in Pacific Gas & Electric Co. Today, the Court opens a wide and inviting door to indirect regulation by juries authorized to impose damages to punish and deter on the basis of inferences even when a plant has taken the utmost precautions provided by law. Not only is this unfair, it also could discourage investment needed to further the acknowledged national need for this alternative source of energy. I would affirm the judgement of the Court of Appeals.