Police are now setting up a 'film them and dob them in' scheme for millions of phone users.

There are certainly rewards to be had, but what are the risks?

Caught, captured and convicted - mobile phone vigilantes being used in the fight back against crime.

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If you have a mobile, you can catch an offender in the act.

A road rage incident was captured after 48-year-old mechanic David Driscoll dived for his mobile phone. A motorcyclist attacks an elderly driver, and despite fears for his own safety, Driscoll continued to film.

Using the video footage police were able to arrest a man in his fourties, who faced court today charged with assault and criminal damage.

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Police now want to harness the smart phone technology in your pocket.

Urging us to upload vision like that onto new police Facebook pages known as Eyewatch in New South Wales and Victoria.

New South Wales Chief Inspector Josh Maxwell says “it's a world first program from a New South Wales police perspective.”

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In the nine months since being established in New South Wales, Eyewatch Facebook sites across the state have had 29 million hits.

“We’ve had robberies, theft, graffiti, stealing, fraud offences, traffic offences a whole myriad of offences,” Maxwell said.

Victoria is now following suit, updating Neighbourhood Watch and bringing it online.

Brian Samuel is president of Neighbourhood Watch Victoria and says “we're really encompassing the entire population. One of the beauties of Facebook is it's being picked up by young people, but older generation as well.”

Currently being trialled, Facebook sites are being created for each individual police region to be launched later this year.

You can use the page to upload photos of dangerous accidents or crime, to alert police, and receives police updates. There's also an emergency button to connect to triple zero.

Footage, like a violent street robbery in Perth which was captured on a mobile, can be used by police to identify the attacker.

But there are risks to consider if you decide to film a crime.

Lawyer David Galbally QC warns you could become a victim yourself.

“The problem with taking photographs of crime is the perpetrator may well attack you to grab the evidence of him committing the crime, and to silence you from giving evidence,” Galbally said.

The other major issue is remaining anonymous. If you film a crime and then use Facebook to upload the footage, it will of course show your name and photo.

“You expose yourself at risk for someone to come and look at it to see what you're doing, and maybe to attempt to remove it, or remove you form giving evidence,” Galbally said.

If you are going to record an incident, Samuel says to be smart about it. “It would only be a fool that would sit there and make it obvious that they're actually taking a photograph. If I saw a crime that was happening, and I could see myself being put in danger, the answer is I wouldn't take the photograph.”

A similar system has been successful in the United States. Their pages also reveal the locations of sex offenders.

• Project Eyewatch - www.police.nsw.gov.au