The NSA was created by President Truman in 1952 through a secret memo, and Congress was kept in the dark.
FBI was not created by Congressional legislation
according to Wikipedia:
The Bureau of Investigation (BOI) was created on July 26,1908, after Congress had adjourned for the summer. Attorney General Bonaparte, using Department of Justice expense funds, hired thirty-four people, including some veterans of the Secret Service, to work for a new investigative agency.Its first chief (the title is now known as director) was Stanley Finch. Bonaparte notified Congress of these actions months later in December, 1908.
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