19 retired four-star admirals and generals, and former secretaries of the Army, Navy, and Air Force, who have served under each President from John F. Kennedy to Donald J. Trump, have filed an amicus brief with the Supreme Court (pdf), warning of disastrous results should the Court agree with Trump’s theory of presidential immunity. Excerpts below; I have bolded some text for emphasis.
Petitioner’s theory that the President is absolutely immune from criminal prosecution, if accepted, has the potential to severely undermine the Commander-in-Chief’s legal and moral authority to lead the military forces, as it would signal that they but not he must obey the rule of law. Under this theory, the President could, with impunity, direct his national security appointees to, in turn, direct members of the military to execute plainly unlawful orders, placing those in the chain of command in an untenable position and irreparably harming the trust fundamental to civil-military relations….
...the rule of law is critical to the military’s mission and to the people’s trust in the armed forces. The military service members’ duty to disobey unlawful orders plainly illustrates this point. This duty requires service members, who are bound to obey all lawful orders, to disregard patently unlawful orders from their superiors and prohibits service members from using such orders as a defense to criminal prosecution. Immunizing the Commander-in-Chief from criminal prosecution, as Petitioner argues for here, would fly in the face of that duty, creating the likelihood that service members will be placed in the impossible position of having to choose between following their Commander-in-Chief and obeying the laws enacted by Congress… Not only does Petitioner’s approach threaten to inject chaos into military operations, it also threatens to damage—potentially irreparably—the public’s trust in the military and the willingness of recruits to join the armed forces.
….the notion that predicted defiance of the Commander-in-Chief’s orders is the backstop against criminal behavior by a President is not what the Constitution provides for. It would inexorably lead to deep divisions between the armed forces’ political and military leaders and would place servicemen and women in the impossible position of either ignoring presidential orders they are sworn to obey or committing crimes at the President’s behest in violation of their oath—for which they may be prosecuted.
I. Petitioner’s claimed immunity would undermine our nation’s foundational commitment to civilian control of the military….
Civilian control of the U.S. military ensures that the armed forces are subordinate to the direction and control of a President who is accountable to the people…. Ensuring that this system works, however, requires more than just laws. It also requires deep trust between the civilian and military leaders that they fundamentally share common goals: to defend the nation and uphold the Constitution and the laws of the United States. Indeed, at its core, civilian control of the military requires mutual trust and respect for the different roles that civilian and military leaders are called to fill in our Constitutional order. In particular, our system requires trust in the Commander-in-Chief as a source of legal and moral authority to lead the men and women of the armed forces, as at his orders they place their lives in peril to serve their country.
Allowing the Commander-in-Chief to weaponize the powers of the U.S. military to criminal ends with impunity would also confront the President’s civilian appointees and military officers with an impossible choice: whether to obey the orders of the Commander-in-Chief or the laws of the United States. Some political appointees might prioritize their loyalty to the President above their oaths and transmit the orders to violate the law, thus passing on to senior military leaders the dilemma of whether to obey the President or the law….
II. Petitioner’s claimed immunity would undermine the military’s adherence to the rule of law and thus its orderly functioning and public trust….
Granting the President absolute immunity from criminal prosecution would threaten the good order and discipline that allow the armed forces to maintain a fighting force capable of protecting the safety of all Americans. Allowing for such immunity also would undermine our nation’s trust in the military as a revered institution situated above and apart from the political fray….
Petitioner’s [Trump’s] amici claim that the My Lai Massacre serves as evidence that the military would not carry out the President’s hypothetical order to murder or assassinate a political rival. Officers’ Br. 12. That is wrong: the very fact that Calley felt emboldened to kill civilians on the basis of “superior orders”—in that case, from a captain—demonstrates that our system remains vulnerable to the risk that servicemen or women may commit crimes when ordered to do so. That risk is all the graver if the person giving the orders is the President, particularly one protected by absolute immunity. Amici are also incorrect in assessing the consequences of My Lai. Among other things, the hero of the incident, Hugh Thompson—who disobeyed Calley’s orders and testified against him—became a target for death threats and harassment fordoing so. The fallout from disobeying a presidential order would no doubt be far more severe….
...our legal system does and should continue to subject the President to criminal laws—just like every other individual in the chain of command—thereby lessening the likelihood that unlawful orders are issued in the first instance and reducing the risk that service members would be required to engage the precarious safety valve of the duty to disobey. Otherwise, our nation risks splintering the chain of command essential to training, organizing, and deploying service members efficiently and effectively across the globe, thereby jeopardizing the orderly functioning of our military….
… Petitioner’s theory would also remove specific checks on presidential authority over the military. For example, the Posse Comitatus Act of 1878 (“PCA”) criminalizes the use of the armed forces to enforce civilian laws, subject to exceptions “expressly authorized” by Congress. 18 U.S.C.§ 1385.5 The PCA thus prevents Presidents from deploying the military within the United States to police civilian “compliance” with laws such as voting regulations. But, absent the availability of criminal prosecution for a President’s violation of the PCA, this important check on military power would be weakened if not eliminated….
III. Petitioner’s claimed immunity, by implicating the peaceful transition of power in particular, threatens national security….
A stable, orderly presidential transition is essential to our national security. Military leaders abroad closely watch the United States as administrations transfer responsibility from one to another so that they can accurately advise political leaders on appropriate security measures. Unstable transitions of power—not to mention any attendant constitutional crises—risk catastrophic misperceptions abroad, emboldening our adversaries, demoralizing our allies, and causing chaos at home….
