It’s hard to miss 53 empty seats on the federal bench. And when a quarter of the world lacked a U.S. ambassador last year, editorial boards noticed. But the Senate’s failure to confirm the U.S. Department of State legal adviser—a figure of ubiquitous relevance in national security and diplomacy—has yet to draw the attention it deserves.

With roughly 200 lawyers, the Office of the Legal Adviser is known in its circles simply as “L,” which is at once a sign of the office’s importance, and the narrowness of its circles. “Just as the solicitor general is the government’s point man for constitutional questions,” says a leading treatise, “the legal adviser is the government’s principal expert in international legal affairs.” To put it more pithily, if the solicitor general is the 10th justice, then the legal adviser is the second secretary of state. Or, at any rate, the secretary of state’s legal superego.