The States should prevail, because under the Constitution the Federal Government does not have police powers and under the 10th Amendment police powers are reserved for the states.
Now the limit on the Federal government police powers has eroded slowly (like all limitations on the federal governments power under the constitution), so you could point to the FBI, secret service, ICE/CBP...but if the Federal Government prevails it would be a giant leap in erosion of State rights and limitations on Federal powers. Basically it would be negating the 10th Amendment and authorizing the Federal Government to establish their own police and unilaterally deploy them nationwide.
In short the States should prevail based on police power and 10th amendment arguments, but I wouldn't foreclose this being the spark the Federal Government is looking for to gain the police powers they have always wanted. If the Federal Government prevails over the States here, you can anticipate a "commerce clause" argument where the Federal Government will use mental gymnastics to claim State failures to police their States effect interstate commerce, so the Federal Government must have the right to step in with their own police powers and regulate.
That’s the plenary “police power” you’re thinking of, and it has a lot more to do with the constitutionality of legislation than with actual police work. It doesn’t mean that federal officers can never engage in police-like activities.
We have seen federal agents acting as police and detaining and arresting individuals on the streets over objections from the Governor and Mayor.
If you are going to support these acts:
1. Cite any legal precedent where Federal government has policed and made arrests over state/local government objections?
2. Identify the Federal Criminal Statute any of the suspects violated authorizing these "arrests"? (presumably even if you believe the Federal government has the power to police over State/local objections, you hopefully agree they don't have the power to make arrests without probably cause a crime was committed, so what is are the federal criminal statutes?)
3. Now even supposing the Court did side with the Federal Government, finding that they have police powers they may unilaterally deploy over objections from local governments and that the arrests here were lawful, you would still tons of other Constitutional issues. For example: in all the arrests I have seen, I have not seen any miranda warnings, post arrest I have yet to find any confirmation the arrestees were afforded their constitutional rights to an attorney...seeing as the Federal agents to date have not had these traditional police powers I think it is fair to assume they haven't received this basic training, and for that reason alone even if the Fed had these powers they are still likely violating numerous constitutional rights in each arrest.
Taking a guess, the reason they're kidnapping many people just to release them without charges is because they're fishing for people with out of state IDs to strengthen the claim of federal jurisdiction. The lack of arrest paperwork fits with this - if they kept a paper trail of all their plainly unlawful attempts, it would risk upsetting whatever narrative they use to charge the unlucky ones.
It may also be partly about proactively anticipating civil lawsuits for false imprisonment and other violations of civil rights. If there is no record of these arrests it will frustrate future civil claims, where the Feds will just deny ever arresting claimants and for the most part unless on video there will be no evidence of the claim.
Since this took place outside the Federal Courthouse during a riot where members of that group were attempting to burn down the courthouse, the Federal Officers have jurisdiction to arrest and prosecute any suspects at the event.
The officers in question have no duty to identify nor use police marked vehicles (note their uniform DOES say POLICE on it).
As long as the officers present the suspects in court with convincing evidence that they were personally involved, they're going to federal prison.
source: Best friend is a federal officer.
tldr: Do not try to burn down a Federal Courthouse. You will not pass Go. You will not collect $200.
It will turn out the way everything else turns out in the age of fruit fly attention spans and everyone trapped in arms races for that attention - https://en.wikipedia.org/wiki/Red_Queen%27s_race
Now the limit on the Federal government police powers has eroded slowly (like all limitations on the federal governments power under the constitution), so you could point to the FBI, secret service, ICE/CBP...but if the Federal Government prevails it would be a giant leap in erosion of State rights and limitations on Federal powers. Basically it would be negating the 10th Amendment and authorizing the Federal Government to establish their own police and unilaterally deploy them nationwide.
In short the States should prevail based on police power and 10th amendment arguments, but I wouldn't foreclose this being the spark the Federal Government is looking for to gain the police powers they have always wanted. If the Federal Government prevails over the States here, you can anticipate a "commerce clause" argument where the Federal Government will use mental gymnastics to claim State failures to police their States effect interstate commerce, so the Federal Government must have the right to step in with their own police powers and regulate.