"States 'are legally permitted to prosecute federal officials for state crimes – within limits', Bryna Godar, a staff attorney at the University of Wisconsin Law School, wrote in an explainer in July. 'The limits stem from the federal constitutional principle that states should not be able to undermine federal policy via targeted criminal prosecutions, a doctrine known as supremacy clause immunity. But this principle only applies when federal officials are reasonably acting within the bounds of their lawful federal duties.'”