This power of the committee can lead to a phenomenon known as Iron Triangles. An Iron Triangle is a stranglehold on policy related to a field due to a common interest and position of the relevant committee(s), the executive branch agency responsible for enforcement, and the producer interest group.
For instance, in the 60s and 70s, there was an Iron Triangle around Nuclear power between the Joint Congressional Committee on Atomic Energy, the Atomic Energy Commission (executive branch), and the large utility companies. For over two decades these groups kept nuclear energy moving forward until it was broken up in the mid 70s.
Today the most notable Iron Triangle is around Agricultural policies. This exists between the Agricultural Committees, the Department of Agriculture, and the large food companies (most noted (and most targeted) being Monsanto).
These three bodies gather support from each other through mutual relationships, much like a collusive relationship between business. This is illustrated by the diagram below (courtesy of the Wikipedia article)
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