Dickstein served as U.S. Representative for various congressional districts in New York from 1923 to 1945.

In 1934, he co-led the McCormack–Dickstein Committee, which investigated Nazi propaganda in the United States and was a precursor to the House Un-American Activities Committee (HUAC).

• Soviet archival records made public in 1999 indicated that he had been a paid agent of the Soviet NKVD in the late 1930s.

• He later served as a justice of the New York Supreme Court from 1946 to 1954.

• He was a member of the Democratic Party.