In this case the trial judge failed to hold an evidentary hearing regarding the alleged contact via social media (Facebook) between a juror and expert witness. The lesson for judges is that an evidentary hearing should be held to determine the nature of the contact and whether a mistrial is warranted.
Link to TN Supreme Court opinion: http://www.tsc.state.tn.us/sites/default/files/smithwdopn.pdf
