"When the FBI arrests a mafia don on RICO charges, when DEA arrests a drug kingpin on narcotics charges, when ATF arrests an unlicensed gun dealer for illegally shipping firearms..."

"... they do not need a green light from the state. And consider for a moment the concept of a 'sanctuary city.' That is a municipality that obstructs the federal government’s enforcement of the immigration laws. The concept would make no sense if the feds needed the state’s permission – the state would simply refrain from asking the immigration authorities to conduct arrests and deportations. Cities purport to become 'sanctuaries' only because the local authorities realize that the federal government has an independent obligation to enforce federal law; they can’t prevent the feds from coming in, so they try to impede federal action.... Federal officers in Portland are not a military force. They are deputized law enforcement agents of the Department of Homeland Security and other federal police agencies. They are not, as Senator Paul misleadingly suggests, 'rounding up people at will.' They are making arrests based on probable cause that laws enacted by Congress have been violated. To my knowledge, Senator Paul has not proposed any legislation to repeal federal penal statutes that prohibit, for example, mutilating federal property, arson, and conspiring to oppose government authority by force...."

From "Portland riots – it is Trump's constitutional duty to enforce federal law and he should/The Constitution says it's the presidents job to enforce the law" by Andrew McCarthy (Fox News).

ADDED: I've encountered SO many law professors who were outraged that the Supreme Court took the position that the federal government couldn't FORCE local government officials to participate in the enforcement of federal law. I've written law review articles on this subject and participated in symposia, so I know what I'm talking about. The key case is Printz v. United States, which was about a federal law (the Brady Bill) that required local law enforcement officials to do background checks on gun buyers. The Court, in an opinion written by Justice Scalia, said that the federal government could not commandeer local government to do its law enforcement work. If it wanted background checks, the feds had to do it themselves (or get local government do it voluntarily). The dissenters — Stevens, Souter, Ginsburg, and Breyer — all said the federal government could force state and local government to enforce federal law even if they adamantly opposed the policy. It seemed that every law professor I ran into thought the dissenters were right (and Scalia was awful). If you think the feds can force local government to enforce federal law, how could you possibly think the feds can't enforce federal law unless the locals request it?