Facebook photos, YouTube videos, Twitter posts, chatroom logs and mobile phone footage are increasingly being used in the courtroom or as background research for barristers, solicitors and the police, writes Sarah Sharples

In Western Australia, an anti-Semitic video posted on YouTube will be used to test the state's new anti-vilification laws. In New South Wales, Facebook photos with captions such as "getting drunk" and membership of the group "I secretly want to punch slow-walking people in the back of the head" were used as character evidence.

In London, mobile phone footage from the G20 summit of a policeman pushing over newspaper vendor Ian Tomlinson, who died ten minutes later, initiated an investigation. In the US, there is an entire industry now dedicated to issuing subpoenas to Facebook.

These are just some examples of how social networking sites and mobile phone technology are an increasing presence in our legal system.

Criminal barrister Matt Johnston has used social networking sites and chatrooms for background research on cases in the last few years as the notoriety of the information available became publicised in the media.

"We're not stalking people," he insists. "All we're doing is accessing information they've put in the public domain. In the old days, people had private investigators following people around and videotaping them without their knowledge.

"The staggering thing to me is Facebook allows you to limit what can be seen by others and some people have no limitations and are prepared to conduct their entire lives in public."

Johnston, who has a Facebook account but does limit his profile, says the decision to conduct life so publicly can come back to haunt people.

"An example may well be a case where there were two people suspected of having a role in supplying drugs. You act for one person and the other person has a profile on Facebook which tends to suggest they have high attendance at dance parties ... and you can even sometimes see comments to the effect that suggest drug usage. Now that may well be relevant," he says.

Sophie Dawson, partner in communication law and IT disputes at Blake Dawson, says we are at the tip of the iceberg for online content being the subject of litigation, especially with privacy and defamation disputes.

"A big issue, for example, is teenagers 'sexting' each other -- sending each other lewd messages. There are going to be questions when those teenagers grow up about whether if, for example, they take down all copies of the material, they can reasonably expect others to keep it private," she says.

"So if one of them becomes Prime Minister, for example, whether or not that person would be able to use a cause of action to say 'Well, it's highly offensive to publish messages now that I posted myself when I was a teenager.' So there is going to be a lot for courts to grapple with there in the future, because the current generation is publishing a lot more about themselves than anyone else has in the past."

Currently the law is murky in Australia as to whether a cause of action for breach of privacy exists, but the Australian Law Reform Commission has recommended it be legislated.

Dawson says that as Generation Y and Z grow up and regret publishing material about themselves, courts will have to decide between two competing views surrounding privacy.

"You can certainly argue that if someone has published something about themselves then they can't reasonably expect it to be kept private, but the counter argument is you can say, 'They were only 12 or 13 or 14 at the time -- they were a child.' So if they have changed their mind as an adult, then they can reasonably expect it to be kept private.

"But it may be that those young people are actually reducing their future privacy rights by publishing those things," says Dawson.

Legal experts have also expressed concerns about social networking sites allowing comments to be made over the character of an accused before a trial. Such an example is in Queensland, where 18 year-old Callum Keys was charged with murder and not long after, Facebook groups emerged discussing his character, alleged motive and guilt.

Patrick Cunning, partner in the technology and information property group at Mallesons Stephen Jaques, says it is not new for the public to weigh into the debate on cases, but traditional media such as talkback radio provide a vital difference.

"With most traditional media there are filter mechanisms that are built in to the system, so with your typical call-back arrangement there is the seven or 10-second delay ... where an announcer or host can kill comment if they believe it is likely to amount to a contempt of court [or if a caller is] commenting adversely on a trial or being defamatory," he says.

"In a social networking site or a blog there typically isn't that sort of moderator role being played."

The anonymity that online sites afford can also be a concern, says John Fairbairn, partner in commercial litigation at Clayton Utz.

"There are recent reports of fake sites being set up with Twitter, where Kanye West was complaining about the fake Twitters out there," he says.

"So you can't be sure, merely because something is posted under someone's name, that it is their material. But having said that, in the courts, there are mechanisms for dealing with authenticity of documents."

This includes using forensic experts that deal in computer technology to examine the IP address for the source of the material and also obtaining the help of the host of the site, says Fairbairn.

However, the use of information from social networking sites is not necessarily all negative, according to Johnston, who says access to information can not only direct how to run a case and cross-examine, but can also benefit his clients too.

"One of the real problems is people forget where they were and what they were doing and it may well be they actually have an alibi. ... We often get clients to go back through their bank, email and Facebook records and find out what they were doing on that day," he says.

But when it comes to a person's online presence, Fairbairn does have some advice. "With online, what you're doing leaves some sort of footprint and the dangers that these sorts of cases show is increasingly that footprint is being used in court cases," he says.

"So when people are posting this material thinking that it is just remaining between their friends or within a particular group, it is in fact available to anyone, including prosecutors and including persons who want to take steps to prevent them from doing unlawful acts."