[syshum]

>>US states cannot just ignore federal law

They absolutely can and do. State government are under no compulsion to enforce federal law, nor do they have aid federal law enforcement. Sure the FBI can still arrest you but as a practical matter the federal government relies heavily on local law enforcement for support in their efforts and task forces.

The state governments can neuter federal enforcement by refusing to supply personnel and equipment or other support to federal law enforcement task forces and actions

Conversely the federal government also supplies (i.e bribes) local law enforcement with money, and gear to grease the wheel for that support.

The supremacy you are referring to with the Supreme court is about when Federal Law and State law conflict then Federal law would win over State Law. Personally I think this is bad but until there is a constitutional amendment to change it that is the reality. However that supremacy does not mean state law enforcement or governments must enforce federal law, only that they can not overrule/supplant a federal law with their own

>> A topical and obvious example is that the current Roe vs. Wade controversy just couldn't happen in the EU - as it's unrelated to trade or competition

Well according to the Current Draft our federal government did not have the power either. It is funny you mention trade, you do know that ACA is a trade regulation the constitutional power that allows ACA to exist is the interstate commerce clause of the US Constitution, that was MASSIVELY expanded in power by the court in the abomination / disgraceful 1942 Wickard decision which effectively made every activity a commercial interstate activity that can be regulated by the federal government.

Personally if the court is in the mood for over turning precedent someone should take a case to them aimed squarely at over turning that abomination, putting the federal government back into their proper scope and place

[B1FF_PSUVM]

On the other hand, I still remember how, back in the 1980s, U.S. states that were reluctant to raise beer-drinking age from 18 to 21 were brought to heel: no federal funds for highways, I think it was.