Lawyers will give their closing arguments today in Suffolk Superior Court in the case of the Commonwealth v Tim Cahill. The former state treasurer is charged with using state funds to run TV ads intended to boost his 2010 campaign for governor. While it may have been wrong to pay for the ads in this way, Cahill is by no means the first politician to use public funds to promote his or her own “brand” but the challenge is always knowing where to draw the line. Mostly the incidents that cross or come too close to the line are dealt with by the state ethics commission with criminal prosecutions pretty rare. Cahill’s case is different because he had a nasty falling out with his political consultants some of whom jumped ship to the campaign of his Republican opponent (Cahill was running as an unenrolled candidate). In the resulting civil litigation, emails that otherwise would have gone undiscovered burst into public view and the Attorney General’s Office felt compelled to prosecute.

Having spent a good deal of time in courtrooms dealing with juries in a prior career, I know better than to try to predict the outcome of a trial viewed only from afar. I will comment on one phenomenon seen in the Cahill trial which is the defendant taking the witness stand in his own defense, something that Cahill did.

At the end of the testimony in any jury trial, the judge instructs the jury in the law relevant to the issues in that particular case. In a criminal case, the judge tells the jury that the burden of proof is entirely on the prosecution and that the defendant has no burden. If requested by defense attorneys in a case where the defendant chooses not to testify, the judge will also instruct the jury that they are to draw no inferences from the defendant not testifying; that they are not even to consider it. Most people (including most lawyers) believe that notwithstanding such an admonition, the jury would have difficulty getting beyond the “not hearing the defendant’s side of the story” stage of analysis and would draw negative inferences, consciously or subconsciously, from that absence.

While that may be true, my experience was that a more powerful dynamic overcame that situation. People who serve on juries overwhelmingly tend to be conscientious and serious about their task. And their task really is to scrutinize the evidence placed before them during a trial. If the defendant does not testify, the jury’s scrutiny lands on the evidence presented by the prosecution. Because the prosecution’s burden is to “prove each and every element of the crime charged beyond a reasonable doubt”, the focus of the jury – directed by the defense attorney’s closing argument – is on the “reasonable doubts” that may lurk in the prosecution’s case. Often the jury will discover such a doubt and, as the law requires, the defendant is entitled to the benefit of that doubt and may be found not guilty.

When a defendant testifies, that entire dynamic shifts. The jury’s scrutiny lands upon the defendant, his testimony and his demeanor on the witness stand. Since most defendants are not accomplished politicians like Tim Cahill, they usually fare very badly on the witness stand. And even in the case of someone like Cahill, cross examination by a skilled attorney can make a testifying defendant look evasive, shifty or worse. Assessing the defendant’s performance on the witness stand becomes the primary task of the jurors and, when the defendant doesn’t do so well, it makes it tough for the jury to then go back and poke holes in the rest of the evidence. Those holes, which in the absence of the defendant’s testimony might lead to acquittal, become easier to dismiss and a guilty verdict is more likely to be reached.

If Tim Cahill is convicted, will it be his own fault for choosing to testify? Not necessarily, since as I said earlier, no one who hasn’t sat in the courtroom for an entire trial can really understand the dynamics involved in that particular case. Still, the “defendant taking the stand” phenomenon may have something to do with the outcome, whatever that may be.