Certainly sanctioned or fined European banks would have the ability to challenge the measures in a US court. On the other hand, sanctions on a state are usuall

Certainly sanctioned or fined European banks would have the ability to challenge the measures in a US court. On the other hand, sanctions on a state are usually met with an equivalent response, and the only question is how powerful the other side is. In the case of the EU, the answer is, not powerless. Look, the US has a lot of cards to play. But randomly bullying banks who didnt do anything wrong, as per your suggestion, is not a particularly effective one, so they won't do that.