A level of technology based on the very best (state of the art) control and treatment measures that have been developed or are capable of being developed and that are economically achievable within the appropriate industrial category.

The best economically achievable technology that reduces negative impacts on the environment.

A technical term used to describe the best and most stringent technology, treatment techniques, or other means available for controlling emmissions, effluent, waste materials, etc. after considering field, rather than solely laboratory conditions. Molycorp is required to use the best available technology in its mining operations unless it can be demonstrated that it is unfeasible for energy, environment or economic reasons.

Best Available Technology (or just BAT) is a "spare no expense" doctrine which prescribes the acquisition of the best technology available, without regard for traditional cost-benefit analyses. This can be the result of a future-oriented business strategy, or reflect concern for other factors, such as environmental impact. Some doctrine deem it already acquired the status of customary law.