As the Justice Department’s Office of Legal Counsel (OLC) has concluded, the dual-officeholding ban “embodies an important policy designed to maintain civilian control of the Government,” and serves “to bar the appointment of regular military officers to any appointive positions in the civil government, irrespective of the importance of the office, the permanence of the appointment, or the likelihood of interference with the officer’s military duties.” After all, as one of the original sponsors of the bill—Massachusetts Senator Charles Sumner—argued, allowing active-duty military officers to hold such positions would be “in conflict with the fundamental principle of republican institutions,” since it would imply that questions of civilian governance would be resolved, in the first instance, by the military. In that regard, the dual-officeholding ban serves much the same purpose as the Posse Comitatus Act—the 1878 law that bars domestic use of the military for ordinary law enforcement absent express congressional authorization.
As with the Posse Comitatus Act, Congress has carved out a handful of exceptions to the dual-officeholding ban over the course of its history (providing, for example, that the CIA director can be an active-duty officer). But those exceptions prove the rule, and the dual-officeholding ban otherwise continues to “prohibit continuation of [an offending officer’s] military status … upon appointment to a covered position,” as OLC concluded in 2016. That’s why, among other things, Mattis and Kelly had to retire from the military before they could join Trump’s Cabinet. (Congress usually requires an additional seven-year waiting period for secretaries of defense, which it waived in Mattis’s case.) And it’s why, as the White House clarified later on Wednesday, Jackson will also be separating from the Navy before he is confirmed. Otherwise, his confirmation as secretary of veterans affairs would have terminated his military commission. (In contrast, the national-security adviser can be an active-duty officer because that position does not require Senate confirmation.)
But even as the Trump administration has seamlessly and unhesitatingly complied with the dual-officeholding ban with respect to its Cabinet appointments, there is a case pending in the Supreme Court in which the Justice Department is quietly attempting to denude the ban of most of its force—arguing that, even when a military officer is appointed to a civil office in violation of the statute, there’s no legal consequence for the violation. If the Court embraces the government’s position in Dalmazzi v. United States (in which I am counsel of record to the Petitioners), it would not only open the door to far more military officers serving simultaneously in senior civilian positions, but it would fly in the face of what the Court has previously described as “the traditional and strong resistance of Americans to any military intrusion into civilian affairs.”