The constitutional prohibition against ex post facto laws only applies to criminal law (Calder v. Bull). So this objection does not apply.
and reversed a court's opinion
No it didn't. Rather, it offered a new avenue of action.
No it didn't. Rather, it offered a new avenue of action.
And, as noted, it's hardly uncommon for the legislature to decide it doesn't like a court decision and pass a law to undermine its basis. One very clear and unambiguous example was a Supreme Court decision late in the nineteenth century which ruled that piano rolls were mechanical devices rather than music, and thus that the producers of piano rolls were not required to seek permission from or pay royalties to the composers of music played by the rolls. The Supreme Court decision was right and proper given the copyright law in effect at the time, but within a year the copyright laws were changed so as to explicitly include mechanical music devices.