In order to address the scourge of abandoned sites where hazardous substances were threatening the environment, the Congress enacted a law in 1980 which was dubbed "Superfund" because one of its provisions created a Hazardous Substances Response Fund, which was originally financed largely by taxes on petroleum and certain chemical feedstocks.  The EPA is authorized to utilize the Fund monies to respond to releases of "hazardous substances" and other pollutants.

Superfund is also generally known as CERCLA, the acronym for the Comprehensive Response, Compensation and Liability Act.  The provisions of Superfund that deal with private party liability for the cleanup of facilities have had a profound effect upon real estate ownership, operations that deal with hazardous substances, and valuation and transfer of businesses with potential responsibility for remedial costs.

Basically, a "release" is a defined term meaning the discharge, disposal, emission, escape, or other allowance of "hazardous substances" to enter the environment from or at a facility. Activity inside of buildings and exhaust of vehicles, planes, trains, etc. are excluded. "Hazardous substances" is a very broad term, encompassing essentially all chemical compounds that are regulated under the various major environmental laws such as the Clean Water Act, Resource Conservation and Recovery Act and Clean Air Act.  Hundreds of compounds are "hazardous substances", including chemicals that are found in consumer products and household waste.

If EPA identifies a location as appearing to present a substantial environmental threat on account of a release of hazardous substances, it can examine and respond at the location itself.  However, EPA is authorized to and commonly does send Notices of Potential Responsibility to persons it believes are connected to the problem in one of three ways: 1) ownership or operation of the facility, 2) transportation of hazardous substances to the facility, or 3) generation and arrangement for disposal of the hazardous substances that are at the facility.

A person receiving a Notice form the EPA is often called a "PRP".  At a given location, there may be dozens or even hundreds of PRPs.  The Superfund is interpreted to impose strict liability on persons who are shown to have been connected to the problem as owner/operators, transporters or generator/arrangers.  Where multiple parties are involved, the law generally imposes "joint and several" liability, which means that each individual responsible party is liable for the entire remedial response.  The law does allow for findings of "several" liability only, where a given share is allotted a party. Arguments and processes among and between PRPs over their "fair share" have thus eaten up enormous amounts of time and expense, especially where the overall responsibility is in the tens or hundreds of millions of dollars at a given Superfund Site.

Congress has been considering improvements to the Superfund liability and allocation scheme.  Specific protection has been accorded persons who "own" sites only as security for financial obligations, and there are limited defenses and exclusions from liability for "innocent purchasers" and people who inherit property.

EPA has the power to issue Orders to responsible persons to perform a cleanup.   Failure to obey without good cause can result in trebled damage liability.

EPA maintains a National Priority List (NPL) of sites that are the worst in terms of environmental threat.  The placement of a facility on the NPL requires notice and opportunity for comment.

The Superfund law includes a title dealing with Natural Resource Damages.  EPA and State Natural Resource damage trustees may seek compensation for the value of lost resources, such as animal life, that are shown to result from given activities.

Liability for Superfund remedial response costs and for Natural Resource damages may be imposed upon persons even though the activity which allegedly caused the liability was perfectly lawful at the time it occurred.  Also, it has been held Constitutional that Superfund liability may be retroactive to occurrences prior to the passage of the law.   Superfund reform has been urged by business, insurance and other groups that believe this sort of cost imposition is unfair.