alt Hacker NewsCitation needed. My reference goes all the way back to 1937 and is specific to independent agencies.
> Almost fifty years of experience has accustomed lawyers and judges to accepting the independent regulatory commissions, in the metaphor, as a headless 'fourth branch' of government.
Source: 1984 Columbia Law article, referencing the 1937 Brownlow Committee Report. https://scholarship.law.columbia.edu/cgi/viewcontent.cgi?art...
Also Wikipedia: "The independent administrative agencies of the United States government may also be referred to as a ‘fourth branch’." https://en.wikipedia.org/wiki/Fourth_branch_of_government
The full paragraph you're excerpting from Wikipedia is much less convincing:
> Such groups can include the press (akin to the European 'Fourth Estate'), the people (in sum or as grand juries), and interest groups. The independent administrative agencies of the United States government, while technically part of any one of the three branches, may also be referred to as a ‘fourth branch’.