Readers write about the polio vaccine and the dread of the disease in the past. Also: Reducing crime; the Unabomber’s victims; health insurances woes.

The president-elect and the president are in transition.

An evidence-based approach to criminal justice would tell us that policing works and long prison sentences do not.

Readers discuss the Supreme Court case and the threats trans people face. Also: Recess appointments; Social Security; pardons; brain injuries and crime.