Conversation so far:
What was the Chicago Eight trial about?
Hoffman was arrested and tried for conspiracy and inciting to riot as a result of his role in anti-Vietnam War protests, met by a violent police riot in 1968.
Were any others being tried with Abbie Hoffman?
Abbie Hoffman was among the Chicago Seven (originally known as the Chicago Eight), which included Jerry Rubin, David Dellinger, Rennie Davis, John Froines, Lee Weiner, future California state senator Tom Hayden
and who else besides Jerry Rubin, David Dellinger, Rennie Davis, John Froines, Lee Weiner, and Tom Hayden was tried with Abbie Hoffman in the Chicago Eight trial?
Black Panther Party co-founder Bobby Seale (before his trial was severed from the others).

Question: What happened that they became known as the Chicago Seven rather than Eight?
Self-contained rewrite: What happened that the Chicago Eight became known as the Chicago Seven rather than Eight?