Abie Roehrig, a twenty-year-old undergraduate, has put his name on a list of volunteers for a human-challenge trial to test the efficacy of a COVID-19 vaccine. A human-challenge trial for a vaccine would be nearly unprecedented: it would entail giving subjects a candidate vaccine against the virus, and then infecting them deliberately to test its efficacy more quickly than a traditional, safer vaccine trial. Larissa MacFarquhar talks about this highly controversial proposal with the epidemiologist Marc Lipsitch, who supports such trials for COVID-19, and the virologist Angela Rasmussen, who feels that the scientific benefits are too limited to justify the enormous risks. Plus, Jelani Cobb speaks with the legal scholar Ira P. Robbins about the shooting death of Ahmaud Arbery, and why prosecutors declined  for months to arrest the white man who killed him. In the Arbery case, Robbins sees a fatal confusion of citizen’s-arrest laws, stand-your-ground doctrine, and racial profiling.