If Brett Kavanaugh were on trial for sexual assault, all he’d need do is demonstrate reasonable doubt about the charges being made against him. But a Republican nominee to the Supreme Court is tried in the media, where Mr. Kavanaugh must now do the impossible: prove an assault never happened.

Christine Blasey Ford alleges that at a high-school party 36 years ago, 17-year-old Brett Kavanaugh pinned her to a bed, tried to remove her clothes, and covered her mouth so she couldn’t scream. Ms. Ford, now a professor at California’s...