This process is legally referred to as \"strict, joint, and several liability.\" The liability is retroactive, meaning that companies lilre Hooker Chemical can't avoid paying for the cleanup because there were no laws regulating the dumping of hazardous waste when they were in business. [Hooker Chemical is now owned by Occidental Petroleum. Strict, joint and several liability also means that laccidental Petroleum is now liable for Hooker Chemical's pollution.)