Person-of-the-year awards are almost always bestowed on men and women who already meet with fawning praise. Let’s instead craft an award based on a person’s willingness to speak truth to power—whether to the press, the boss, or to partisan operators. Call it Adult of the Year. The winner: Attorney General William Barr.

President Trump nominated Mr. Barr in December 2018, and for a moment he received the respect he deserves. The press had grown accustomed to demeaning all Trump nominees, but was stymied by Mr. Barr’s impressive...