The U.S. Chemical Safety Board is authorized by the Clean Air Act Amendments of 1990 and became operational in January 1998. The Senate legislative history states: "The principal role of the new chemical safety board is to investigate accidents to determine the conditions and circumstances which led up to the event and to identify the cause or causes so that similar events might be prevented." Congress gave the CSB a unique statutory mission and provided in law that no other agency or executive branch official may direct the activities of the Board. Following the successful model of the National Transportation Safety Board and the Department of Transportation, Congress directed that the CSB's investigative function be completely independent of the rulemaking, inspection, and enforcement authorities of EPA and OSHA. Congress recognized that Board investigations would identify chemical hazards that were not addressed by those agencies. The legislative history states:
[T]he investigations conducted by agencies with dual responsibilities tend to focus on violations of existing rules as the cause of the accident almost to the exclusion of other contributing factors for which no enforcement or compliance actions can be taken. The purpose of an accident investigation (as authorized here) is to determine the cause or causes of an accident whether or not those causes were in violation of any current and enforceable requirement.
Although the Board was created to function independently, it also collaborates in important ways with EPA, OSHA, and other agencies. The Board has entered into a number of memorandums of understanding (MOUs) that define the terms of collaboration. For example, in cases where several agencies are conducting investigations of a particular accident, the MOUs outline mechanisms for coordination in the field. The goal of the MOUs is to allow each agency to carry out its statutory mission efficiently and without unnecessary duplication of effort.