The Supreme Court decision on Masterpiece Cakeshop vs Colorado Civil Rights Commission keeps noting, not just that the original incident happened in 2012, but that the legality of things had since changed:
Page 1:
... because of his religious opposition to same sex marriages—marriages that Colorado did not then recognize—...
Page 2:
... His dilemma was understandable in 2012, which was before Colorado recognized the validity of gay marriages performed in the State and before this Court issued [decision] ... Given the State’s position at the time, there is some force to Phillips’ argument that he was not unreasonable in deeming his decision lawful...
Etc, etc. These comments suggest that the concept of ex post facto laws would come into play, but nowhere in the discussion have I seen them mentioned. Why is that?