Nevertheless, there is a lot of evidence to back him up on this: Almost all state prosecutors are elected, and they are partisan players, often seeking publicity in a bid to run for higher office. To give them the unchecked power to subpoena a president would be an invitation for the most ambitious partisans in the reddest or bluest localities to harass future presidents of the opposing party.
Manhattan District Attorney Cyrus Vance has provided reason to worry about overly political state prosecutors. His critics claim he has too often shielded the powerful while harshly punishing minor crimes of have-not New Yorkers. In 2012, he allegedly overruled his own prosecutors, dropping a potential fraud
(The House Democrats have also given good reason for federal courts to scrutinize politically-charged subpoenas. The House subpoenas earlier this year asserted a bad faith pretext of “legislative purpose,” when everyone knows that the House had a mix of motivations—some political, like seeking information to damage Trump in public opinion, and some more legitimate, like investigating high crimes and misdemeanors. For narrowly political reasons, the House leadership was hiding its real reasons—impeachment—to protect Democrats from conservative districts. It is reasonable for courts to demand the real and good faith reasons for subpoenas, not pretexts, especially in cases infused with a mix of partisan and valid legal motives. The House has subsequently fixed this problem, but their earlier pretexts still cast a shadow on their investigation.)
Because of these dangers, presidents have a good argument for federal jurisdiction—for at least some degree of federal court review of criminal procedures to ensure that they meet some standard of good faith, reasonability, and balancing the state interests with the president’s executive privilege. The canonical Supreme Court case on this question, U.S. v. Nixon, rejected arguments for blanket presidential immunity like the one here, but instead used a more functional balancing test taking into account the seriousness of the alleged criminality and the burden on the president of compliance. Federal courts should have jurisdiction to review a state subpoena or indictment, but only in the context of making sure there is reasonable suspicion, and balancing these competing interests, not to automatically block state prosecutors.
The problem is that in making this case, Consovoy inadvertently backed into another problem, one much bigger and more alarming. Earlier in the argument, Consovoy had emphasized the danger of “the proliferation” of hundreds of state prosecutors investigating a president, if all 50 states were “unleashed.” Judge Christopher Droney replied, “How is that different from federal grand juries’ subpoenas? There are a lot of state [prosecutors] but there are a lot of federal U.S. Attorneys, too.”