WASHINGTON (AP) — When police arrested more than 200 anti-Trump protesters on Inauguration Day 2017, it touched off a long-term battle of wits and wills.

On one side: a Justice Department that has sought to incarcerate scores of people over a violent protest that smashed downtown storefront windows and set a limousine ablaze.

On the other side: an intensely coordinated grassroots political opposition network that has made Washington the focus of a nationwide support campaign, offering free lodging for defendants, legal coordination and other support.

The stand-off entered a home stretch last w...