What is the fine-grained topic of the following text: Haas has an extensive background in mass defense from his days as a lawyer for Black Panthers and co-founder of the People’s Law Office, a Chicago lawyers’ collective that rose up to meet its historical moment—the defense of hundreds of Vietnam War protesters in the aftermath of the 1968 Chicago Democratic Party convention. Only return the topic.
Haas's background in mass defense and co-founding the People’s Law Office