> OK, AIUI the law in Spain means that only central gov can order a referendum. The vote was declared illegal and those party to it were thus breaking the law, conspiring to harm the constitutional standing of the country.

My understanding is the same. Which is why I wrote above that they should have gone out and actually arrested the separatist leaders who organized all this. This could have played out in the courts (up to the Court of Justice of the European Union, I would guess).

But sending a few thousand (or tens of thousands?) police against millions of voters was not about this. Whatever they thought they were trying to do, it was not possible with these numbers. And as far as I can tell, they did not try to arrest people. They did not try to get people's personal data to get them before of a court at some other point. They did not show up in time to simply barricade the doors of polling stations. In short, they were not enforcing or upholding the law in any meaningful sense.