This is wild - according to this article in the New York Times, a suspect accused of carrying a loaded weapon subpoenaed the arresting officer's MySpace and Facebook status messages.  Those messages and the officer's internet postings were key to an acquittal.

Gary Waters was on trial for carrying a loaded weapon.  He argued that he was beaten up by the arresting officers who planted the weapon on him.  Waters's lawyer, Adrian Lesher, sounds like a resourceful guy.  He tracked down a slew of illuminating internet postings by one of the officers:

• the officer's MySpace mood message was set to "devious" hours before the arrest
  
• a few weeks before trial the officer's Facebook status message said:  "watching ‘Training Day’ to brush up on proper police procedure”
• (commenting on video clips of arrests on the internet where a suspect was punched) the officer said “if he wanted to tune him up some, he should have delayed cuffing him....if you were going to hit a cuffed suspect, at least get your money’s worth 'cause now [the officer is] going to get disciplined for' a relatively light punch."

Is Social Media Evidence Different?  I fall into the camp of those who resist "social media exceptionalism".  There's a tendency to think that our ability to communicate using new tools such as Facebook/Twitter will somehow revolutionize communications, advertising, and everything else in life.  (It's tough to deny that social media is not fundamentally changing the face of advertising, marketing, journalism and public relations (to name a few - the legal profession maybe as well?).)  From a legal standpoint, in particular, I think that social media should be treated no differently than any other media.  Lawyers tend to get alarmist about it, but it's a lot like email, although more readily accessible.  However, this article made me think twice. 

From the standpoint of use of social media in courts, I think Walter Olson sums it up best - people probably post stuff on the internet about ongoing legal matters because they think their "personal thoughts" are not discoverable or usable as evidence: 

I think this really highlights what catches many lawyers and clients by surprise as far as social media: the legal system allows for the use of the personal thoughts of opponents and third parties as evidence.  In fact, this is often some of the best evidence, and why emails are often so valuable.  Emails (status messages and tweets) are often the best window into what a person was thinking at a given time.  Diaries and personal letters were always admissible, but lawyers would have to go through an awful lot of trouble to track down someone's diary or personal letters.  If the witness denied that they maintained a diary or wrote a letter, there was not much the lawyer could do to verify.  Now things are different, since the bulk of communications take place online, and much of the communications are publicly accessible.  The personal thoughts of a witness or party are an internet search away.

Evidentiary Issues?  The question often arises as to whether social media evidence is admissible.  A thorough exposition on this topic is beyond the scope of this post, but social media evidence will (more often than not) be admissible.  A variety of theories will support their admission into evidence.  A statement made by a witness via social media is "hearsay," - an out of court statement.  Hearsay statements are typically inadmissible, but a variety of exceptions and exclusions exist.  The evidence could be a statement by a party opponent - any statement by a party opponent is admissible under an exception to the hearsay rule.  Social media evidence can also be used for impeachment purposes.  An out of court statement can typically be used to impeach a statement of a witness.  Finally, the evidence is likely admissible as a "present sense impression".  Statements that are made in the heat of the moment or which reflect what the witness was thinking at the time of the statement are also admissible as exceptions to the hearsay rule. (Hearsay is defined as an out of court statement which is used to prove the truth of the matter asserted...if a statement is not used to prove the truth of the matter asserted it's technically not hearsay.)  At the end of the day, social media evidence will typically be admissible, and will reflect a "digital trail" of what a person is thinking.  The Waters case referenced in the New York Times article highlights it well. 

The Tweeting Juror?  There's also this:  "Juror Tweets at Issue in Arkansas Civil Trial."   One of the big stories of the day was that a juror sitting on an Arkansas civil case which resulted in a multi-million dollar verdict tweeted about the jury's deliberations (or tweeted after  the deliberations).  Here's one of the tweets in question:

These tweets are now the basis of a motion for a new trial.  I think it will blow over, but this story illustrates the significance social media now plays in the judicial process.  The story also highlights the fact that lawyers should have a conversation - at a minimum with their clients, if not with others involved in the case - about social media and how it may affect the case.  People have always had conversations that have the possibility of landing them in hot water.  However, in today's day, rather than chatting with a friend over coffee or a beer and spilling the beans, they now broadcast their words to the entire universe, where they are (1) permanent and (2) easily searchable.