There's an ironic addendum to the story about Mark Felt's decision to be Bob Woodward's Deep Throat. It takes place a little later on, when Felt was committed to finding and stopping the members of the anti-war group the Weathermen.
The Weathermen grew from the civil rights and anti-war movements of the late 1960s. It declared itself not just opposed to the federal government, but committed to its overthrow. It carried out bombings against government entities across the country, including the New York City police department, the San Francisco Hall of Justice, and the National Guard Association building in Washington, D.C.
J. Edgar Hoover had prohibited what the FBI referred to as “black bag jobs” in the last months of his life. Following Weatherman bombings at the Pentagon and the Capitol in the early 1970s, though, FBI Director Patrick Gray gave Felt free reign in tracking them down. This would come to include burglaries and surveillance operations on family members and associates of Weather Underground members.
Felt, Gray and another FBI official were indicted for these burglaries in 1978. These same break-ins, moreover, would cost the FBI the ability to charge and try members of the Weather Underground for their crimes once they surrendered to authorities.
Throughout his trial, Felt had kept his contact with Woodward limited; he was under a huge amount of stress, and was also nervous about his prospects for a presidential pardon should he be outed as Deep Throat. During his trial, former President Richard Nixon testified in Felt's defense and the Washington Post editorialized against him.
Woodward was curious to hear how Felt rationalized his behavior. The last time he called to talk to his old ally, Felt angrily pointed out the irony: Nixon came to his defense, while the Post impugned him.
Woodward and Felt didn't speak again for over twenty years.