A class action has been filed against Rockwell International Corporation and Dow Chemical Corporation on behalf of Colorado property owners adjacent to the Rocky Flats Nuclear Weapons Plant who allege that, over the years, the plant released a six-mile high plume of highly radioactive plutonium contaminating over 15,000 parcels of land in violation of state and federal environmental laws. The action seeks compensatory damages for diminution in the value of the properties and punitive damages under theories of trespass, nuisance, negligence, and strict liability.

During the Cold War, the federal government used the Rocky Flats facility to manufacture nuclear weapons. Dow Chemical operated the plant from the 1950s through 1975, and Rockwell International operated it from 1975 to 1989. The landowners sued in 1990, after the Federal Bureau of Investigation and the Environmental Protection Agency in 1989 raided the Rocky Flats headquarters seeking evidence of violations of environmental laws at the facility. As a result of the investigation, in 1992 Rockwell pleaded guilty to 10 hazardous waste and other environmental law violations and agreed to an $18.5 million fine.

The court determined that Colorado tort law will govern the proceedings, so the landowners will not have to prove that plutonium contamination on their property presents a health risk or otherwise caused actual or substantial damage to their properties as an element of their trespass claims. This ruling was influenced by a recent Colorado Supreme Court decision that stated "that the migration and presence of contaminants upon another's property constitutes a physical invasion that is actionable under the traditional rule of trespass."

For the nuisance claim, which is predicated on the right of a person to use and enjoy that person's own property, the court held that the property owners do not need to prove an actual, scientifically verifiable health risk stemming from the plutonium contamination on their property to prevail. It stated that the law of nuisance provides countless ways in which the plant can substantially interfere with the landowner's use and enjoyment of land, including interference with the physical condition of the land itself, disturbance in the comfort or conveniences of the occupant including his or her peace of mind, and threat of future injury that is a present menace and interference with enjoyment.

The action seeks compensatory damages for the period during which the plant was in operation, but asks for punitive damages only for pollution that occurred prior to August 20, 1988.