>Because as far as I’m aware, immigration law is not a concern of the state, and what folks typically mean when they say “nullification” in this context is “the state isn’t doing the fed’s job for them.”

It's not just immigration law, it's any federal law. States have the right to ignore federal law if they like. This is called nullification. However, it very, very rarely happens because its inherently undemocratic. It especially rarely happens to the extent that cities and states pass explicit laws that order state law enforcement to ignore federal laws, and even work against the federal government's interests.

It's happened recently with marijuana legalization, with success. Where the federal government did some raids, but marijuana legalization is politically popular, so they backed off... and there has even been talk in some years of ending the illegality of marijuana federally.

State nullification has been somewhat unsuccessful with illegal immigration. These raids are the result of the federal government going its own way to enforce the law without cooperation of the states. The last time we saw this level of federal enforcement against state objection is after Brown v Board of Education: https://en.wikipedia.org/wiki/Little_Rock_Nine

I good comparison to the seriousness of nullification as an act that is inherently an escalation is gun control laws. Suppose some red states wanted to just nullify the National Firearms Act -- https://en.wikipedia.org/wiki/National_Firearms_Act -- The are perfectly in their rights to ignore federal laws and allow firearms dealers to sell unregistered, suppressed, machine guns to felons. The only way neighboring blues states -- obviously outraged that this is happening -- can do anything about this is by seeking federal enforcement, again, which would include raids, arrests, etc.

>You also brought up warrants to enter private property. What do you make of the incident a few days ago where an agent hopped a fence to arrest someone, without a warrant? Should we just ignore those violations of our rights?

I'm very much not saying ICE is always acting within the law. Like any other policing force, they're going to make mistakes (intentional or otherwise). We should be very angry about those things, especially if they're happening in bad faith. The problem I see is that when we're yelling about actually -- and unfortunately -- legal things then those serious issues are just going to look like background noise. The other serious problem is that all this crying wold literally makes the left look undemocratic. You don't like the law? Fight to change it. Don't just take the ball and go home, and then cry when the neighbors come to your house to get the ball back.