The Trump administration’s global tariffs face their first major legal test this week when a little-known Manhattan court considers one of the president’s most sweeping assertions of executive power. A three-judge panel at the Court of International Trade will hear arguments Tuesday on whether to halt the levies, which have unleashed a trade war with the world and threaten to upend the global economy. The federal court, which has nationwide jurisdiction over tariff and trade disputes, operates for the most part in obscurity, rarely garnering a mention in major publications and staying off the radar of most attorneys. “Most lawyers...