Regulatory capture is a theory associated with George Stigler, a Nobel laureate economist. It is the process by which regulatory agencies eventually come to be dominated by the very industries they were charged with regulating. Regulatory capture happens when a regulatory agency, formed to act in the public's interest, eventually acts in ways that benefit the industry it is supposed to be regulating, rather than the public.
Public interest agencies that come to be controlled by the industry they were charged with regulating are known as captured agencies. Regulatory capture is an example of gamekeeper turns poacher; in other words, the interests the agency set out to protect are ignored in favor of the regulated industry's interests.
