With all the circus around the Trump Administration, nothing is more dangerous to democracy than the sanctuary city status that many U.S cities invoke. Why? For local elected officials (such as mayors) to unilaterally violate federal law (righteous or not) becomes a slippery slope.
Today it is illegal immigration enforcement and tomorrow it could be IRS tax crimes. If a U.S. city ignores the laws of the land, it will lead to nothing short of chaos. I hope and pray that there is some wisdom in our current elected local government that can avert a lighted match in a keg of powder.