It's TMI - too much information, in the language of the Internet, cell phone texts and social media posts.

Easy juror access to cyberspace is a growing problem for courts, whether it involves the criminal trial of Baltimore's mayor, an Anne Arundel County murder trial or a Florida drug case.

Last week, a Maryland appeals court upended a first-degree murder conviction because a juror consulted Wikipedia for trial information. Earlier this year, the appeals judges erased a conviction for three counts of assault because a juror did cyberspace research and shared the findings with the rest of the jury. In a third recent trial, a juror's admission to using his laptop for off-limits information jeopardized an attempted-murder trial.

On Friday, lawyers for Baltimore Mayor Sheila Dixon asked for a new trial in part because five of the jurors who convicted her of embezzlement Dec. 1 were communicating among themselves on Facebook during the deliberations period - and at least one of them received an outsider's online opinion of what the verdict should be. The "Facebook Friends," as Dixon's lawyers call them in court documents, became a clique that the lawyers argue altered jury dynamics.

While the world of Google and Twitter indulges boundless curiosity, judges do not.

Jurors are told to reach a verdict based only on what the judge allows to be admitted at the trial, and not research or discuss the case. Everything else is out, following complicated legal rules of evidence.

But information that a decade ago was inconvenient for inquisitive jurors to learn is now at their fingertips, on their cell phones, hand-held devices and laptops. Social media didn't exist. That is leading lawyers and judges to gnash their teeth over what they believe is a growing problem of jurors Web-surfing and posting their thoughts.

"If I were a Circuit Court judge, I'd be thinking this goes on all the time," said Byron L. Warnken, a law professor at the University of Baltimore. "People probably believe they can do it and not get caught."

The issue is not peculiar to Maryland. The American Bar Association noted that in March, an eight-week federal drug trial in Florida ended in a mistrial - not because one juror tattled to the judge that another had resorted to cyberspace searches about the case. After asking all 12 jurors, the judge learned that eight others had Web-surfed, too.

Appeals elsewhere are based partly on jurors' posts on Twitter and Facebook, according to the ABA, with worries about the lack of control and breach of trust.

Concern has grown so much nationwide that legal experts, including in Maryland, are rewriting model jury instructions to specifically tell jurors that online searches, texting and social media - the things they routinely do on laptops, cell phones and BlackBerrys - are out. Maryland's rules are expected to be published next year, and the ones on that subject are still being drafted.

Most judges specifically tell jurors not to look up anything connected to the case online, going beyond the warning to stay away from the news and not discuss the case with each other until deliberations start or with anyone else until the trial ends. Courts confiscate jurors' cell phones and hand-held devices during a trial - but short of sequestering jurors, judges cannot control jurors going online or texting at other times.

Jurors doing their own investigation and talking about their cases is not new.

"The problem is accentuated by the availability of information," said Baltimore County State's Attorney Scott D. Shellenberger.

A decade ago, jurors who wanted to see the neighborhood where a crime took place had to go there; now, they can see it on Google Earth from a BlackBerry. They can check out a defendant's criminal past on Web sites, witnesses on Facebook, and what users think about a company on consumer blogs - all information that probably was excluded from evidence. Sharing thoughts about a pending case now may include jurors' social media posts that anyone can read.

Last week, the Court of Special Appeals voided the 2008 first-degree murder conviction of Allan Jake Clark, accused of beating a man to death in 2007.

In the jury room, a bailiff in the Anne Arundel County Circuit Court trial had found printouts of Wikipedia explanations of scientific terms. Judge Paul A. Harris Jr. denied the defense's request for a mistrial.

Writing for a panel of the Court of Special Appeals that overturned the conviction, Judge Charles E. Moylan Jr. said that an "adverse influence on a single juror compromises the impartiality of the entire jury panel."

Particularly important was that the Wikipedia definitions discussed details of how the settling of blood after death can help determine the time and place of death - which were issues at Clark's trial.

In May, the court erased the 2007 conviction in Baltimore of Zarzine Wardlaw on three counts of assault. During deliberations, a jury note advised the judge that one juror told the rest of having researched "oppositional defiant disorder" online and that ODD is associated with lying. That was critical to the credibility of a person who made allegations against Wardlaw, the appellate judges wrote.

In November, a juror in the attempted-murder trial of Jerold Raymond Burks in Anne Arundel County admitted during deliberations to having Web-surfed to read news stories about the case. But not everything he shared with fellow jurors was still accurate. Neither the prosecution nor defense sought a mistrial. The jurors were told correct information - but that subject had not been part of Burks' trial. He was found not guilty.

In the Dixon trial, Judge Dennis M. Sweeney warned jurors repeatedly not to text, tweet or in any way discuss the case outside the deliberations room. But five apparently became Facebook "friends" and their postings on one another's public Facebook walls mention the case.

In court filings, Dixon's lawyers wondered what they wrote to each other in private Facebook messages - all contrary to Sweeney's instructions.

"I wouldn't want a juror to go online and look at my Web site and say, 'Look, he is proud of getting murderers off, we're not going to let that Jezic get one more,'" said Andrew V. Jezic, a board member of the Maryland Criminal Defense Attorneys' Association.

Particularly in criminal cases, witnesses may have criminal records - which may not be divulged at trial but could damage jurors' perceptions of them, he said.

"More and more states are including an expanded and more specific instructions [to jurors] that they shouldn't do it and it's improper. Newer-pattern jury instructions around the country will refer to Twitter and Facebook and all of these new things that the younger generation is so familiar with," said Irma S. Raker, retired judge of the Maryland Court of Appeals, who chairs a panel updating Maryland's instructions.

"If I were a Circuit Court judge, I'd be to the point that not only can they not take anything into the jury room, but telling them that they could be held in contempt if they violate the court's order," said Warnken, who is also working with the panel.

Others fear that the threat of contempt - which can carry a fine or jail time - is too harsh.

"I do think they should tell them the consequences of their hard work could be disrupted and that there could be a mistrial or a conviction overturned, or a civil judgment overturned," said Shellenberger, the Baltimore County prosecutor.