But it won’t be heard in the courtroom...
I'm sure a lawyer will set me straight if I'm wrong here but even if the judge rules before the trial that this stuff can't be introduced as evidence my understanding of the law is that if the prosecutors,or prosecution witnesses,utter a single syllable about what a fine,gentle young man Saint Trayvon was that opens the door for the defense to prove otherwise...including by introducing stuff like this.
The defense can use this evidence in a self defense case to rebut any inference by the prosecutor that the dead guy was of a peaceable and non-violent character. It is used to show that the dead guy was in fact the initial aggressor.
The prosecutor just has to raise the inference of peaceful character in their case in chief. It could be as little as a one of Martin’s family members blurting out “Trayvon was a good boy!” I think it will be difficult for them to keep this door closed. Not impossible, but very difficult. Zimmerman’s attorney is going to do his best to pry that door open and then run through like a Heisman Trophy winner.
Keep in mind that the evidence that then becomes relevant is limited to evidence showing a propensity for violence. The fight text is appropriate. There have been other posts indicating that Trayvon had photos of pot plants. That would not be relevant, and no, those photos are not relevant to show he was high on the occasion of his death. The toxicology results establish that, and evidence that Trayvon liked to get high on other occasions will not be admissible.
The above is based upon ~30 years experience as prosecutor, criminal defense attorney and judge.