This article is part of a series from the November 2017 Harvard University conference entitled “Presidential First Use: Is it legal? Is it constitutional? Is it just?” To access all of the transcripts from this conference, click here.

We need to construct a credible legal institution within the executive branch to constrain the president’s unilateral war-making powers and insist that he gain the consent of Congress before making any use of nuclear weapons. This is required both by the Constitution and by the War Powers Act of 1973. Up through the 1970s, the Office of Legal Counsel (OLC), in the Justice Department, served this crucial function as legal guardian. Its elite staff of 30 civil service lawyers were charged with writing opinions on contested issues of law within the executive branch. A special statute specifically made these opinions binding on the military. This law remains on the books, but the OLC no longer credibly operates as the executive branch’s legal conscience.

Until the Nixon Administration, the OLC generally had only one political appointee, the assistant attorney general, who was in charge of the office. The hard work of opinion writing was executed by those 30 civil service lawyers, who had a deep understanding of the legal traditions established by generations of executive branch practice. Nowadays, career lawyers are very much in the minority, and high-powered political appointees often take the lead in opinion writing. While executive branch traditions continue to play a role, many OLC opinions now look more like advocate’s briefs for the sitting president than balanced assessments of applicable statutes and doctrines.

Worse yet, even these partisan opinions no longer play the authoritative role once accorded to the OLC. Instead, the Office of White House Counsel now calls the shots on issues high on the president’s agenda. This rival team of high-powered lawyers did not even exist until 1969, when John Dean was appointed counsel to the president. Before that moment, the White House counsel was a position reserved for one of the president’s trusted political advisors. The counsel’s legal tasks were so minimal that he did not need a legal staff to help him out.

Dean was only 31 years old when he took up the position of White House counsel. Since he was far too young to assume the counsel’s traditional function as senior advisor, he hired four staff lawyers to take the legal side of the job seriously. This experiment had an inauspicious beginning, since Dean and his staff played a critical role in the Watergate cover-up. But over the next decades, the White House counsel’s office escaped from its scandalous beginnings, and is now slightly larger than the OLC. Moreover, its 35 or 40 positions are swept clean with every administration, in favor of a whole new set of high-powered lawyers, whose principal qualification is their long-standing support of the sitting president and his policies.

Given the constant turnover, the White House counsel’s office has no institutional memory, and many of the appointees don’t have much personal experience with any number of crucial areas that raise fundamental legal issues. For example, Robert Bauer was the White House counsel at the time of the war against Libya. He had been a lawyer for the Democratic National Committee and a personal lawyer to President Obama. He knew very little about national security law. Yet he intervened decisively on the question of whether the president was required to gain Congressional approval for his bombing campaign against Libya in 2011.

Obama refused to do so, fearing that Congress would say no. But the War Powers Act of 1973 was designed with precisely such a case in mind. It provides that if the president fails to gain Congressional authorization within 60 days of initiating hostilities, he must cease all military operations within the next 30 days. As the 90th day approached, the Office of Legal Counsel began preparing an opinion that took the statute seriously and advised the president that he should stop bombing.

In response, Bauer told the OLC to stop work on its opinion, and began to search the executive branch for another legal office that would write a legal-looking opinion that came out with the opposite answer. His quest led him Harold Koh, the State Department’s legal adviser, who obliged with a highly creative “interpretation” of the statute that allowed the president to keep on bombing past the 60–30 day deadline.

The “Bauer-Koh” moment marked the total disintegration of the OLC’s function as legal guardian. From then on, the OLC was on notice that if it did not give the president what he wanted, his White House counsel would suppress publication of their opinions and find a different executive branch lawyer to back the president up.

The rule of law suffered yet another body blow, in 2014, when President Obama embarked on a sustained campaign against the Islamic State, on September 10. This time around, the administration issued no opinion at all within the 60–30 day period that even purported to justify its escalating war against ISIS. It merely asserted that the Congressional authorizations for the use of force against Al Qaeda in 2001 and Saddam Hussein in 2002 should be expansively interpreted to authorize Obama’s war against ISIS in 2014.

I represent Captain Nathan Smith, who has served as an intelligence officer in the command headquarters in the ISIS war, in a lawsuit. That suit charges that Obama’s bare assertions of authority, recently reasserted by the Trump Administration, cannot survive serious legal scrutiny, and that the ongoing military campaign against ISIS is illegal under the War Powers Act. Smith vs. Trump is presently under consideration by the Court of Appeals for the DC Circuit, and may well go to the Supreme Court for final resolution. A victory in this case would be a large step forward in vindicating Congress’s constitutional authority as the ultimate arbiter on the question of war and peace.

Nevertheless, even a favorable Supreme Court decision won’t be enough to stop Trump or future presidents from waging unilateral wars during the long years that future Captain Smiths will need to convince future justices to intervene decisively in the name of the rule of law. America needs a powerful legal guardian within the executive branch to take the plain language of the War Powers Act seriously, and tell the president, in published opinions, that he must stop his unilateral military campaigns at the 90-day limit, or else breach his constitutional obligation to “take care that the laws be faithfully executed.” Such a pronouncement could well trigger the inauguration of impeachment proceedings, and only a particularly foolhardy or self-righteous president would choose to treat the guardian’s words with impunity.