Immigration is the ultimate responsibility of the Federal Government--so via Trump's executive order on Sanctuary cities--(a law that doesn't exist---as Sanctuary City is not defined by any law)--it is the equivalent of you getting fined for the mess your neighbor has refused to clean up in his yard.
There is 'Enforcing Federal Law' then there is 'facilitating violation of Existing law - aiding and abetting criminals'. Liberals - Sanctuary Cities - are
actively, defiantly
violating Federal law, not refusing to enforce federal law.