Banning participation in the enforcement of such laws in some places while other places vigorously cooperate in enforcing said laws is a good way for those here illegally to wind up where they are wanted instead of where they are not. Everybody wins. Community choice wins. Freedom wins. So long as the illegals are not used as bait to get more federal funds that is. People ought to have choices, without expecting others to pay for their choices. So with that caveat, I have no beef with sanctuary cities. It is the essence of localism. Don't lose any sleep because people you have never met in a town you have never lived in are doing things differently than you would.And that brings me to the other "sanctuary cities". There has been talk of having "sanctuary cities" from federal gun laws. Now a few tiny towns have become "sanctuary cities" for the unborn. Enforcement is weak so far. It just makes clear that people can sue those involved in pushing someone to get an abortion. So a private person who is affected still has to sue. The proposed fines would only go live if Roe were overturned. And so far as I know, there are no abortion clinics in these towns anyway. So right now this is mostly symbolic.
That being said, there is one catch to the goodness which can come from local communities exercising their right to dissent from central government laws they consider unjust: the communities must have the freedom to express their dissent in any political direction. If the federal government passively allows communities to skirt federal drug or immigration laws but clamps down on attempts to moderate federal gun or abortion laws, then "Sanctuary Cities" are simply another tool for the left to impose its will on the nation even when out of favor with the majority. Reverse the sides and I would say the same thing.
We are entering a time where federal courts have squandered much of their moral capital with preposterous rulings. It is essential for both the spread of freedom and to maintain the credibility of the courts that they refrain from meddling in the sanctuary city issue, in particular in a biased manner. They can't uphold the principle of sanctuary cities for causes they favor and oppose them for causes they find distasteful and expect to retain any moral authority. That would be an unprincipled course of action which would expose them as mere tyrants imposing their preferences rather than keeping their oaths. So wherever they land on the issue, it should be consistent regardless of the content of the idea. 