Agency of the United States

What does Agency of the United States mean in American Law?

The definition of Agency of the United States in the law of the United States, as defined by the lexicographer Arthur Leff in his legal dictionary is:

An entity (which may be a single individual) which has the power as agent to bind the U.S. as principal. Where used in a statute the term either denotes or connotes something like “high agency” or “high agent,” i.e., an entity of substantial importance and power, e.g., the Interstate Commerce Commission acting as such. (It should be noted that the concept of agency by estoppel is severely limited in its application to the U.S. government as principal.)