A powerful story published by The Atlantic has a serious problem: proof it ever happened. "When social justice activist and lawyer Derecka Purnell was just 12 years old, she and her sister watched a police officer shoot a young boy in a city recreation center because he had ignored the basketball sign-in sheet. This jarring, emotional, and deeply unsettling story was published July 6 at The Atlantic, in the section reserved for ideas, under the bold, attention-grabbing headline, “How I Became a Police Abolitionist.” Purnell’s deeply personal story of shattered innocence and shattered bones at the end of a policeman’s...