By enactment of this chapter the Congress makes exclusive provision for the payment of unemployment benefits for unemployment occurring after June 30, 1939, and for the payment of sickness benefits for sickness periods after June 30, 1947, based upon employment (as defined in this chapter). No employee shall have or assert any right to unemployment benefits under an unemployment compensation law of any State with respect to unemployment occurring after June 30, 1939, or to sickness benefits under a sickness law of any State with respect to sickness periods occurring after June 30, 1947, based upon employment (as defined in this chapter). The Congress finds and declares that by virtue of the enactment of this chapter, the application of State unemployment compensation laws after June 30, 1939 or of State sickness laws after June 30, 1947, to such employment, except pursuant to section
362
(g) of this title, would constitute an undue burden upon, and an undue interference with the effective regulation of, interstate commerce. In furtherance of such determination, after June 30, 1939, the term “person” as used in section
1106 of title
42 shall not be construed to include any employer (as defined in this chapter) or any person in its employ: Provided, That no provision of this chapter shall be construed to affect the payment of unemployment benefits with respect to any period prior to July 1, 1939, under an unemployment compensation law of any State based upon employment performed prior to July 1, 1939, and prior to such date employment as defined in this chapter shall not constitute “Service with respect to which unemployment compensation is payable under an [or “service under any”] unemployment compensation system [or “plan”] established by an Act of Congress” [or “a law of the United States”] or “employment in interstate commerce, of an individual who is covered by an unemployment compensation system established directly by an Act of Congress,” or any term of similar import, used in any unemployment compensation law of any State.