Here’s the abstract for Steven G. Calabresi’s Opinion on the Constitutionality of Robert Mueller’s Appointment (2018):
I argue in this Legal Opinion that Deputy Attorney General Rod Rosenstein’s appointment of Robert Mueller is unconstitutional both under the test for officer inferiority set forth in Justice Scalia’s opinion in Edmond v. United States, which is cited as good authority in Free Enterprise Fund v. PCAOB and also under the test for officer inferiority set forth in Chief Justice Rehnquist’s majority opinion in Morrison v. Olson. Under both tests, Mueller is acting as a principal officer even though he has not been nominated by the President and confirmed by the Senate. Mueller’s appointment is therefore unconstitutional.
H/T Criminal Law Prof Blog. — Joe