This juror's action might well cause a mistrial on appeal. I've only ever been on one jury, but the case ended in a mistrial because a prosecution witness inadvertently let the jury know the defendant had a prior arrest record. The jurors are instructed not to discuss the case with anyone, including each other, or read anything about it until the case is in the jury's hands. In Pennsylvania, jurors are allowed to take notes, but those notebooks are collected at the end of each day and not given back to the jurors until they are back in the courtroom. Jurors are sent out of the court room pretty frequently so they are not influenced by any point the attorneys are arguing to the judge, etc.

This juror was posting on facebook and twitter. There is simply no way to tell what kind of private feedback this juror may have gotten as a result of the postings and how that might have affected his opinion. No one knows if that, in turn, might have influenced other jurors. Further, I think it's telling that the juror has now deleted everything he posted.

Because this juror is internet/tech savvy, one has to wonder if the juror was reading stories on line or on political blogs during the trial. That would be another no-no.

There are also at least 2 alternate jurors who sit in the jury box and jury room with the 12 primary jurors. They hear all the evidence and only are excluded from voting on the final verdict. I am not a lawyer, but I think the judge may have made a mistake by not granting defense counsel's request and removing this juror from further deliberations and replacing him with one of the alternates.

We have already seen two high profile Bush era DoJ federal corruption trials implode after gaining convictions. One against Siegelman in Alabama and the other against Ted Stevens in Alaska.

pd