I definitely think the defense should call Tracy Martin.
I'm thinking that if Tracy decides to admit to his earlier statement and try to explain it away, he might not be able to get away from his previous position that the police were lying. A lot will depend on what public statements he made in his own voice, without going through his privileged communication attorneys. Tracy did a lot of public speaking in various venues.
I'm not so sure about Robert Sr. It would be powerful symbolism, for the defense to bookend their voice witnesses with GZ's parents, then call the father of TM that the prosecution didn't call. I think the impact of the defense calling Tracy would be weakened somewhat by their not calling Robert Sr.
The flip side is that putting Robert Sr. on would give the state a juicy opportunity to play the race card.
In an earlier discussion,
it was argued that the state would be afraid to go there because they don't know how well Robert Sr. might defend his views. I'm not sure they don't know. His book came out on the eve of trial, but there may have been clues that led the state to explore the issue in his deposition. In any case, why would they care?
Watching and discussing the trial for the last few days, I've developed an appreciation for the importance of focus and momentum. If I were one of the prosecutors, I think I would like nothing better than to have Robert Sr. on the stand all day, holding forth on his opinions about racial relations in America, whether he argues them well or badly. It would be a huge distraction during the defense's part of the case, and break their momentum.
If any of the jurors feel that Robert Sr.'s opinions on these matters are crankish or morally questionable, they aren't likely to change their minds because he argues well.
The prosecution might not go there for a different reason. They seem to be in a hurry to get the case over with, so they might not want to use what amounts to a delaying tactic.
I'm thinking that calling Robert Sr. is a risk the defense would do well not to take.
All of the above is my opinion.