Recently, juror B37 in the George Zimmerman murder trial got and quickly lost a book deal. What is confusing to me, is that such deals are legal in the first place.
During the jury selection process, lawyers for both sides carefully screen jurors to ensure a 'fair' process. Among other things, lawyers attempt to weed out potential jurors who have might have a prejudice which keeps them from rendering a fair verdict and those who might have some stake in the outcome. A book deal potentially creates both a prejudice and a stake in the outcome.
The media attention given to high profile cases creates a pubic appetite for information before, during and even long after the case. If a juror goes into the process with a book deal, movie deal or other potentially profitable venture in mind as a result of the case it shifts their focus. While the focus of the jury should be on justice and a fair outcome, a would be writer needs to focus part of their attention on the story they will tell. It also seems that a controversial verdict lends itself to book sales better than an expected verdict. If O.J. Simpson or George Zimmerman had been found guilty, interest in the cases would probably have waned much more quickly.
Under so-called Son of Sam laws, it is currently illegal in many jurisdictions for a convicted criminal to profit from their crimes. While jurors have not been convicted of anything, it should similarly be illegal for them to profit from the real or alleged crimes of a person they are sitting in judgement over. This is admittedly a limitation on free speech but I feel it is a minor and a necessary limitation.
The focus of juries should be on the case at hand, the facts and merits of the arguments and on rendering a fair verdict. No part of a jurors mind should be devoted to the story they want to tell, how they'd like the story to end or what they will wear on their talk show appearances.