According to this Washington Post article, Martha Stewart‘s appeal is likely to challenge the trial court’s exclusion of expert evidence that her stock trade wasn’t illegal. It appears that the trial judge’s the ruling excluding the expert evidence was based on the finding that the technical legality of the trade was not relevant to the question of whether Ms. Stewart had a motive to obstruct investigations into the trade. Presumably, the judge would have allowed Ms. Stewart to testify as to her belief as to the legality of the trade, which would have been relevant on the motive issue. Alas, as we all know, Ms. Stewart elected not to testify during the trial. Nevertheless, the excluded expert testimony represented one of the only ways through which the defense could present its case on the legality of the trade issue without waiving Ms. Stewart’s right not to testify.
Meanwhile, Harvard Law Professor Alan Dershowitz excoriates the Stewart defense team’s decision not to allow Ms. Stewart to testify in this Wall Street Journal ($) op-ed, which includes the following speculation:

One of the most intriguing aspects of the entire Stewart case was never addressed by either side: namely, that virtually every action for which Ms. Stewart was convicted took place after she had consulted with highly experienced and expensive lawyers. As legal ethics expert Stephen Gillers wrote before the trial in The American Lawyer, “defendants ordinarily retain lawyers after they commit their alleged crimes. In contrast, all the crimes charged against Stewart were allegedly committed while she was receiving the advice of excellent defense lawyers at Wachtell, Lipton, Rosen & Katz — one of the nation’s best law firms. Three times, in fact, the indictment’s chronology refers gratuitously to Stewart’s lawyers [though not by name].”
The job of these lawyers was to keep their client out of any further legal difficulties. In doing this job, no lawyer should ever accept a client’s initial account, especially if it is not corroborated by hard evidence. As Mr. Gillers correctly observed, every lawyer knows that “many clients lie even when they have nothing to hide.” Even if the lawyer believes his client is being truthful, he should not allow the client to relate an uncorroborated account to law enforcement officials, unless the lawyer is absolutely certain that the account will not be subject to challenge by the government. (One would think that every lawyer would have learned that painful lesson from Bill Clinton’s lawyer, Robert Bennett, who allowed the president to be deposed about his sex life without corroborating his highly questionable account.) Yet Ms. Stewart’s original lawyers allowed her to make the statements to law enforcement officials that formed the basis of her convictions. It was these lawyers who then recommended her trial lawyer, Mr. Morvillo. (“We decided to add him to our team.”) According to several lawyers familiar with New York practice, Mr. Morvillo and Ms. Stewart’s original lawyers are part of the same “old boy” network of former New York prosecutors who sometimes refer cases to each other. It was Mr. Morvillo who made the decision not to put on any case.
If the Stewart defense team had put on a more complete case, with or without her testimony, the entire story would have become a matter of public focus, to the potential embarrassment of her original lawyers. Whether this factor entered into Mr. Morvillo’s decision not to put on a defense case will probably never be known. There were certainly other more traditional reasons for making that risky decision; but since it turned out to be the wrong one, legal and ethical experts will surely pick up on Mr. Gillers’ perceptive observation by asking whether Mr. Morvillo’s decision may have been influenced — consciously or unconsciously — by considerations other than the interests of his client, Martha Stewart.