Retired General Lloyd Austin, Joe Biden’s nominee for secretary of defense, was legally barred from serving in the job without Congress granting him a special waiver under the National Security Act of 1947. General Austin retired from the Army in April 2016, which is less than the seven years out of uniform required by the statute before serving as secretary of defense. Both the House and Senate voted for that waiver on Thursday by lopsided margins, after having waived the same requirement for James Mattis four years ago. Granting two consecutive waivers was the wrong way to do this. A wiser course would have been to repeal the ban entirely, or at least dramatically shorten it. Congress should do so now. Section 113 of the act, enacted when the War and Navy departments were merged into a much-enlarged Defense Department overseeing a much-enlarged standing military after the Second World War, imposed a ten-year ban on uniformed officers serving as secretary of defense. That was shortened to seven years in 2008. The theory of the ban was to ensure civilian control of the military, both to avoid capture of Pentagon leadership by military-industrial interests and, more gravely, to prevent the growth of an unsupervised standing military that might someday threaten civilian government. Within a few years of its passage, a waiver was granted to let George Marshall take over as secretary of defense after the outbreak of the Korean War. Marshall was, by common agreement, uniquely qualified for the moment, having been chief of staff of the Army throughout World War II, and uniquely safe to entrust with the job, having served as a civilian as secretary of state before his appointment to run the Defense Department. Four years ago, I argued for a waiver for Mattis, the first granted since Marshall. A major part of my argument at the time was that the American republic had gotten by just fine with more-recently-serving military men running the War Department before the ban. Indeed, this stretched all the way back to Henry Knox, as well as with recent ex-generals such as Dwight Eisenhower and Ulysses S. Grant as president. However, there were three other reasons why a waiver for Mattis was particularly appropriate in 2017. First, Mattis was a man of unusual prominence and respect as a thoughtful warrior. He could legitimately be regarded as a man whose reputation inside and outside the armed forces lent credibility and stability to the Defense Department, in addition to qualifying him for the role. General Austin is undoubtedly a well-regarded man (notwithstanding questions about his involvement in Obama-era intelligence handling), but he does not occupy a similarly unique position. Second, there was a shortage of candidates of stature comparable to Mattis. A large proportion of the national-security establishment of the Republican Party (or of independents or conservative Democrats of the sort who might serve in a Republican administration) had been alienated from Donald Trump in the course of the 2016 presidential campaign. Between those who would refuse to serve under Trump and those whom Trump would refuse to hire, the pickings for a first-class defense secretary were slim. There was thus a particular need for Mattis to step up to the task. While the Democrats’ bench of potential defense picks is not exactly inspirational, Austin was not even the favorite among observers of the party; Michèle Flournoy was, having served in senior Pentagon posts under both Bill Clinton and Barack Obama. It is not clear why General Austin would be markedly superior to Flournoy or other potential choices. Third, Trump was new to government and temperamentally unstable, but also potentially subject to the counsel and influence of a strong figure running the military. There was a particular risk that Trump would be in need of someone who knew the ropes. For all Biden’s many flaws, inexperience is not one of them. Nor is impulsiveness; Biden is more apt to be overcautious. Biden will need a serious person in the job who can push back against left-wing efforts to hobble our defense capabilities, but the identity of the defense secretary under Biden is not that likely to have a major influence on the direction of our foreign policy. There are two arguments suggested by Democrats — especially those among the 17 Senate Democrats and 150 House Democrats who voted against the Mattis waiver — for granting a waiver to Austin. One, which is entirely of Biden’s own making, was that declining a waiver for Austin would unduly delay installing a secretary of defense. But this is a hazard of any cabinet nomination that requires Senate approval. If Austin had lost the waiver vote, this would be no different from losing a confirmation vote. The second is the argument that Austin is uniquely valuable because there has never been an African-American defense secretary. Of course, there is some value in getting “firsts” behind us. There is, however, no reason to suspect that he is the only qualified black candidate for the job. Moreover, a country that has now had a black president and vice president and multiple black secretaries of state and national-security advisers is not in immediate, dire need of breaking this particular barrier. Flournoy, the chief alternative candidate, would have been the first woman in the job, and it is as likely as not that if Austin had been denied the waiver, Biden would have prioritized race, gender, or some other form of identity in making his choice. The point of waiving application of a general law is that the circumstances are exceptional. Granting consecutive waivers without identifying an exceptional reason moves us from exception to habit. When declining to enforce a law becomes a habit, Congress should rethink the law. My own preferred solution is to reduce the seven-year period to simply require that the officer be out of uniform until after an intervening presidential or congressional election, in order to reduce the risk of uniformed officers lobbying or campaigning for the job, or being granted political favor, while in uniform. A cooling-off period of that limited duration, similar to those used in various parts of the Constitution, might alleviate some of the potential constitutional objections to Section 113. There is, for now, no obvious reason why the Senate should not confirm Austin, but there was nothing exceptional to justify a waiver. Having voted twice to waive the law, Congress should be honest and change it.