RULE 404. Character Evidence Not Admissible to Prove Conduct; Exceptions; Other Crimes Evidence
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(b) Other crimes, wrongs, or acts. --Except as otherwise provided by Rule 608(b), evidence of other crimes, wrongs, or acts is not admissible to prove the disposition of a person in order to show that such person acted in conformity therewith. Such evidence may be admitted for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity or absence of mistake or accident when such matters are relevant to a material issue in dispute. [/QUOTE
http://www.judiciary.state.nj.us/mcs/rules/part4/part401.html#rule404
Rules of Evidence 608 and 609 are relevant here to:
http://www.judiciary.state.nj.us/mcs/rules/part6/part601.html#rule608
They all basically say that to attack a witness's credibility or propensity for truthfulness, prior criminal history may be relevant. But to show that the witness acted this way in the past and acted the same way in this incident is considered too prejudicial to be relevant. IMO.
I don't practice criminal law and this isn't a legal opinion, just my translation of the information. They want to protect the defendants' rights as provided by law and prevent a mistrial. The jury selection process will already be very difficult at this point.
ETA: The hearsay rule also protects against out of court statements being admitted as evidence, there is something like 25 exceptions and another list of things that are considered NOT hearsay even though they seem to be. So locking statements made out of court down is very common to prevent a violation that would result in NONE of it being admissible at trial.
ETA2: It goes without saying that protecting AC and maintaining his cooperation is huge.
