With President Donald Trump accusing former President Barack Obama of treason, it’s worth recalling the Supreme Court immunity ruling in Trump’s favor that would apply to the prosecution of any former president over their actions in office.

Trump v. United States wouldn’t be the only roadblock to the Trump Justice Department prosecuting the Democrat — indeed, it’s unclear what a criminal case against him would be. Trump’s allegations came as his director of national intelligence, Tulsi Gabbard, claimed that Obama and his national security Cabinet members “manufactured and politicized intelligence to lay the groundwork for what was essentially a years-long coup against President Trump” after Trump won the 2016 election. Gabbard said she’s making a “criminal referral” to the DOJ.

An Obama spokesperson said the former president’s office “does not normally dignify the constant nonsense and misinformation flowing out of this White House with a response,” but added that “these claims are outrageous enough to merit one. These bizarre allegations are ridiculous and a weak attempt at distraction.”....

But if the Trump DOJ charges Obama — again, it’s unclear what statutes the DOJ would use or what the theory of the case would be — among the things Obama’s counsel could point to is the immunity ruling.

And while Chief Justice John Roberts’ opinion didn’t fully flesh out how broadly presidential immunity applies, an important procedural aspect of the ruling is that it emphasized that former presidents are entitled to pretrial immunity appeals. That would be valuable to Obama in this hypothetical scenario, because he could raise the immunity issue at the outset and potentially end the case before it got going.