Section 3(b) in The Dock Workers (Regulation of Employment) Amendment Act, 1980
(b)no suit or other proceeding shall be maintained or continued in any court for the refund of, and no enforcement shall be made by any court of any decree or order directing the refund of, any such contribution which had been received or collected and which would have been validly received or collected if the provisions of section 3 of the principal Act, as amended by this Act, had been in force at all material times;
