[dragonwriter]

> What would happen if one of those states made it illegal to order a drone strike without the approval from one of their courts...could the President be arrested and charged in that state for violating that law?

Probably not, because Supremacy Clause. Federal officers operate in the states fairly regularly, and this general issue (not the specific issue involving the President and drone strikes in particular) has been litigated extensively.

[einhverfr]

it's not even just the Supremacy clause. Generally speaking, the state governments cannot regulate federal agents, nor can the federal government regulate state agents except for things like the equal protection clause.

See Coleman v. Maryland, holding that since the medical leave act provisions under the Family and Medical Leave Act were passed under the commerce clause, not the EPC, then state governments were not bound to it.