§ 3642. Severability. If any clause, sentence, paragraph, or section of this part shall be adjudged by any court of competent jurisdiction to be invalid and after exhaustion of all further judicial review, the judgment shall not affect, impair or invalidate the remainder thereof, but shall be confined in its operation to the clause, sentence, paragraph, or section of this part directly involved in the controversy in which the judgment shall have been rendered. The provisions of this section shall apply to all sections of this part except those sections which are expressly subject to separate severability provisions contained hereinbefore in this part.