A frustrated Chief Justice John Roberts Jr. on Monday grilled a U.S. Justice Department lawyer over why the United States would not take a position on what courts should do in a case the government claims has significant implications for foreign relations.

“You emphasize the significance of the international relations context” for the existence of “comity,” a doctrine of deferring to a foreign nation that could more appropriately resolve certain disputes, Roberts said to Benjamin Snyder, an assistant to the U.S. solicitor general, in the case Republic of Hungary v. Simon. “But your client, the United States, has scrupulously avoided taking a position on what courts should do given the international relations context. This is the perfect time for you to fill that void. Why hasn’t the government told the courts what the foreign relations impact on the United States is?”