(a) In determining the meaning of any provision of this part, unless the context should indicate otherwise, the first three provisions of 1 U.S.C. 1 (rules of construction) shall apply.
(b) If benefits are denied to any individual pursuant to the Act, at 42 U.S.C. 3796a(4), or otherwise because his actions were a substantial contributing factor to the death of the public safety officer, such individual shall be presumed irrebuttably, for all purposes, not to have survived the officer.
(c) Any provision of this part held to be invalid or unenforceable by its terms, or as applied to any person or circumstance, shall be construed so as to give it the maximum effect permitted by law, unless such holding shall be one of utter invalidity or unenforceability, in which event such provision shall be deemed severable herefrom and shall not affect the remainder hereof or the application of such provision to other persons not similarly situated or to other, dissimilar circumstances.
(d) Unless the same should expressly provide otherwise (e.g., by use of the word “hereafter” in an appropriations proviso), any amendment to the Act (or any statutory enactment otherwise directly referent or -applicable to the program that is the subject of this part), shall apply only with respect to injuries (or, in connection with claims under the Act, at 42 U.S.C. 3796(k), shall apply only with respect to heart attacks or strokes referred to in the Act, at 42 U.S.C. 3796(k)(2)) occurring on or after the date it takes effect.