In a nutshell, Florida permits a defendant in a criminal case to introduce evidence of a victim's reputation for violence, providing there is a showing of self defense on the part of the defendant. One purpose is to show that the victim was the first aggressor. When a defendant offers the evidence for this purpose, it is unnecessary for him to show that he had prior knowledge of the victim's propensities. This is because because the evidence is offered to show the conduct of the victim, rather than the defendant's state of mind.
There are still other factors that the court would weigh in deciding if its admissible: Things like when was it, how similar was it to what is claimed in this case, and does the prejudicial nature of the evidence outweigh its probative value.
Until specific evidence is disclosed by one side or the other, it is not appropriate to speculate here or bring up contents of social media accounts and rumors. Those are just character attacks.
Suffice it to say the requests the defense is making are not witch hunts or fishing expeditions. If the state , for example, wants to introduce evidence of Trayvon's good character, the defense has the right to challenge it with evidence it discovers. If it waits until trial, it will be too late. The defense has to anticipate such action by the state and be prepared to meet it.
The Florida Evidence Manual: Section 90.404(1)(b) allows evidence of a pertinent trait of character of the victim of a crime to be offered by an accused; or by the prosecution to rebut the trait; or evidence of a character trait of peacefulness of the victim offered by the prosecution in a homicide case to rebut evidence that the victim was the aggressor.
Trayvon isn't the only person whose character will be subjected to scrutiny by the defense. I would expect Dee Dee to be as well. The state has said she's a critical witness. The defense is entitled to impeach her credibility, even if its just to show her bias.
Murray v. State, 838 So. 2d 1073, 2002 Fla. LEXIS 1942 (Fla. 2002).
Denying a defendant the opportunity to present evidence that a witness is biased not only violates Fla. Stat. § 90.608(2), it also implicates a defendant's constitutional right to cross-examination which is guaranteed by the Sixth Amendment to the United States Constitution and Fla. Const. art. I, § 16; inherent within this right is a defendant's right to expose a witness's motivation in testifying because it is the principal means by which the believability of a witness and the truth of his testimony are tested.
The state can object to the issuance of the defense subpoenas but I don't think it will prevail. If the evidence is reasonably calculated to lead to the discovery of admissible evidence and is relevant to the issues in the case, they probably will be granted.