The law takes affect on a certain date. Thus anything enacted before that date is binding. States cannot enact ex post facto laws.
but they can enact laws dealing with adhesion contracts and coercive contracts.
So it only impacts new hires?
I’m also imagining that Kroger’s got a sweet deal from the union.
I think most folks understand that. What folks wonder about is how parties can enter into a contract which during the currency of the contract will violate public policy in that jurisdiction.
Michigan has passed a "right to work" law which goes into effect on a certain date. Say I apply for a job at Krogers after that date, and Kroger's tells me that I must join a union or pay dues to the union in any case because their contract requires it.
That's not an ex-post-facto law, that's a contract that's illegal as a violation of public policy.
By the way, contracts are not "enacted"; they are simply agreed to by the parties involved - and to be valid, they must among other things, comply with public policy in the jurisdiction where the contract is to be enforced.
The law took effect on the 28th. There are lawsuits pending regarding the long extensions in schools and universities. These extensions will end up being a real disaster for the unions.