Judicial Conference Committee on Court Administration and Case Management issues model jury instruction  “to help deter jurors from using electronic technologies to research or communicate about cases on which they serve.”
With the increasing access to information on a wide variety of portable devices, the courts have had to deal with a new phenomenon: limiting juror access to the Internet or other information during the trial. The facts of any case should be decided based on the evidence introduced at trial and not external information or research. Juror access to Internet information can result in reversal or cast doubt on the validity of the verdict based on motions filed at trial or issues raised on appeal. See, e.g., Juror Internet Research Leads To Reversal  ; No Reversal Despite Juror Exposure To Internet Information, Media Accounts And E-mail. 
In confronting these issues, the trial court may have to wrestle with the general bar under FRE 606(b)  which precludes a juror from testifying on “any matter or statement occurring during the course of the jury’s deliberations or to the effect of anything upon that or any other juror’s mind or emotions as influencing the juror to assent to or dissent from the verdict or indictment or concerning the juror’s mental processes in connection therewith.” However, the rule allows juror testimony on “whether extraneous prejudicial information was improperly brought to the jury’s attention” or “whether any outside influence was improperly brought to bear upon any juror.” Depending on the facts of the case, issues may be raised under the Sixth Amendment Right To A Fair And Impartial Trial.
Given the increasing prominence of juror access to Internet information during trial, the Judicial Conference Committee on Court Administration and Case Management has issued some model instructions “to help deter jurors from using electronic technologies to research or communicate about cases on which they serve.” See Memorandum On The Juror Use Of Electronic Communication Technologies.  The memorandum was sent to all United States District Court Judges. The memorandum notes that the instructions were drafted:
to address the increasing incidence of juror use of such devices as cellular telephones or computers to conduct research on the Internet or communicate with others about cases. Such use has resulted in mistrials, exclusion of jurors, and imposition of fines. The suggested instructions specifically inform jurors that they are prohibited from using these technologies in the courtroom, in deliberations, or outside the courthouse to communicate about or research cases on which they currently serve. The Committee believes that more explicit mention in jury instructions of the various methods and modes of electronic communication and research would help jurors better understand and adhere to the scope of the prohibition against the use of these devices.
The two model instructions, reproduced below, include an instruction before trial and at the conclusion of the trial:
The Use of Electronic Technology to Conduct Research on or Communicate about a Case
Prepared by the Judicial Conference Committee on Court Administration and Case Management December 2009
You, as jurors, must decide this case based solely on the evidence presented here within the four walls of this courtroom. This means that during the trial you must not conduct any independent research about this case, the matters in the case, and the individuals or corporations involved in the case. In other words, you should not consult dictionaries or reference materials, search the internet, websites, blogs, or use any other electronic tools to obtain information about this case or to help you decide the case. Please do not try to find out information from any source outside the confines of this courtroom. Until you retire to deliberate, you may not discuss this case with anyone, even your fellow jurors. After you retire to deliberate, you may begin discussing the case with your fellow jurors, but you cannot discuss the case with anyone else until you have returned a verdict and the case is at an end. I hope that for all of you this case is interesting and noteworthy. I know that many of you use cell phones, Blackberries, the internet and other tools of technology. You also must not talk to anyone about this case or use these tools to communicate electronically with anyone about the case. This includes your family and friends. You may not communicate with anyone about the case on your cell phone, through e-mail, Blackberry, iPhone, text messaging, or on Twitter, through any blog or website, through any internet chat room, or by way of any other social networking websites, including Facebook, My Space, LinkedIn, and YouTube.
At the Close of the Case:
During your deliberations, you must not communicate with or provide any information to anyone by any means about this case. You may not use any electronic device or media, such as a telephone, cell phone, smart phone, iPhone, Blackberry or computer; the internet, any internet service, or any text or instant messaging service; or any internet chat room, blog, or website such as Facebook, My Space, LinkedIn, YouTube or Twitter, to communicate to anyone any information about this case or to conduct any research about this case until I accept your verdict.