How many different ways can you say atrocious? This is the type of movie where the director/ writer, in this case Aaron Sorkin, thinks one of his stars Sacha Baron Cohen as Abby Hoffman is going to win awards and therefore unintentionally goes out and ruins his performance by giving him close-ups constantly and a million speeches to deliver-all with an annoying actorish Boston accent. Then he puts him on the witness stand and has him deliver even more annoying platitudes.
I can't think of another movie in which so many actors of good repute give such horrible hammy performances. Eddie Redmayne has Tom Hayden's pizza face. That's about the extent of his performance. Worst of all is Mark Rylance (a rather short man) playing the rather tall and charismatic William Kunstler. But the way that Rylance plays him, he couldn't convince you that Jesus was innocent.
Surprisingly the best performance in the movie and the only one that has any professional force is Frank Langella's nasty Judge Hoffman. Considering how over the top the direction is that's no small accomplishment.
if you ever want to learn anything about the '60s you'd be much better off watching a fictional movie like Coming Home. What that movie was able to do and what this movie cannot is convey a sense of the free-floating anxiety that pervaded that era. What you get with the Trial of the Chicago 7 is a preachy, arrogant, pompous, speechy mess.