There's no such thing as "states' rights". States, like all levels of government, have no rights.

Government has powers, not rights, and only those powers granted it by Federal/State constitutions.

People sometimes misstate the concept of limited Federal powers as "states' rights", but the term generally reflects ignorance.

The last two times I heard about states rights were:

- Trump wanted to run the Covid response. The states told him to get lost. (Was that good or bad? True, the Covid response has been disjointed, even incoherent. Would it have been more coherent if Trump ran it? Or less?)

- Trump wanted to send federal law enforcement into cities to control rioting. The cities told him no. (There were some federal agents in Portland against the will of the city; the legal scope of their activity was protecting federal property.)

The deal is that we have a limited federal government. They don't get all the power. They get the power the constitution says they get. The states (or the people) get the rest. And they're pretty touchy about protecting that power.

Is it useful? It is if you want to keep having a limited federal government. Arguably, we need (and needed) far more than we have had.

Can you give me a citation about the Trump Covid response? That does not match the reality I experienced.

Not from the top of my head. But I seem to recall Trump saying that we're going to require shutting down, or require masks (don't recall the details), and various governors telling Trump that no, we're not going to, and you can't make us.

A bit the opposite. Trump has consistently downplayed the threat, and the (blue) states have taken it seriously and saved lives. Fortunately it's well within their rights to be more restrictive than the federal government, just like it's within California's rights to have more restrictive emissions laws than the fed. But that's a different argument.

Decentralization.

Sanctuary cities are also a case of states rights. They're not called such, but that doesn't change the fact that it's a local authority telling the federal authority to get lost.