She took on a small Mississippi town’s police. Then they arrested her.

LEXINGTON, Miss. — Handcuffed in the cramped lobby of the Lexington Police Department, standing eye-to-eye with the chief, Jill Collen Jefferson was given a choice. She had been arrested while filming a nighttime traffic stop in this county seat of roughly 1,500 people and four traffic signals. Pay a $35 processing fee, the chief said, and we’ll release you.

Jefferson, 37, a Harvard-educated lawyer and former Obama administration speechwriter, declined Henderson’s offer to let her go if she paid the fee. Instead she stepped into the back of a police cruiser and traced the journey made by dozens of her clients — some beaten, some accused of infractions as minor as driving without insurance — past the town’s Confederate monument, to the county jail.