((a)) ** Prohibition in general** No damages, interest on damages, costs or attorney’s fees may be recovered under section 4, 4A, or 4C of the Clayton Act (, 15a, or 15c) in any claim against a person based on any official action directed by a local government, or official or employee thereof acting in an official capacity.15 U.S.C. 15

((b)) ** Nonapplication of prohibition for cases commenced before effective date of provisions** Subsection (a) shall not apply with respect to cases commenced before the effective date of this Act.