Wikipedia
Interlocking directorate refers to the practice of members of a corporate board of directors serving on the boards of multiple corporations. A person that sits on multiple boards is known as a multiple director. Two firms have a direct interlock if a director or executive of one firm is also a director of the other, and an indirect interlock if a director of each sits on the board of a third firm. This practice, although widespread and lawful, raises questions about the quality and independence of board decisions.
Usage examples of "interlocking directorate".
What had begun in Chicago as a simple sketch of a French athlete turned American culture-hero had developed, by the time I got to Boston, into a series of maddening skirmishes with an interlocking directorate of public relations people.
Military-industrial complex: An interlocking directorate of military and industrial leaders, held to be in effective control of the USA.