Rioters' mobile phones could help police investigation
Police may be able to use rioters' mobile phone information to help convict them, say legal experts.
Investigators can apply to see the contents of text and instant messages, as well as their location.
However, authorities may not be able to access the full wealth of data available to telecoms companies because of legal restrictions.
Guidelines require police to find out individuals' identities first before obtaining records from trouble spots.
Research In Motion, maker of the BlackBerry smartphone, has already said that it will be cooperating with investigations, and pointed out that it is bound to hand over subscriber information when it relates to criminal activity.
The company's BBM instant messenger has been identified as one of the services used by rioters to coordinate their actions.
Under the Regulation of Investigatory Powers Act (RIPA), police can apply for details of a customer's phone records, including their location, details of calls made and received, and internet activity.
But requests must be made for each suspect on a case-by-case basis.
Police would be unable to carry out a broad-based search, identifying, for example, every person who was in Clapham Junction sending the word "riot".
"They would have to say we want this individual's comms data and these are the reasons why," said solicitor advocate Simon McKay, who has written a book on the subject.
"When it comes to the next person they would have to look at that completely separately and re-apply."
Initial identification data would likely need to be taken from video, photographs, CCTV footage and other intelligence.
Those limits mean telecoms subscriber data becomes useful additional evidence, rather than a first port of call.
Mr McKay explained that, when considering requests, the issue of collateral intrusion also had to be taken into account - specifically, how much of other people's data might inadvertently be disclosed, along with that of the suspect.
Such safeguards make investigations extremely labour intensive according to Barrie Davies, a retired chief inspector who now teaches RIPA procedure for Baron Training.
"It is a lot of paperwork," he told BBC News.
"People don't always believe us but there is a lot of oversight that is done by authorising officers to make sure that anything that is done is necessary and proportionate."
Despite the restrictions, some legal experts believe there is scope to push RIPA guidelines further than they have been in the past.
One senior barrister, with extensive experience of this area, told the BBC that doing a "trawl" for mobile phones in a particular location where rioting was taking place might be considered proportionate in this case.
However, he conceded that it was unlikely police would make such a request.
Another possibility, according to solicitor Mike Conradi from DLA Piper, would be for BlackBerry to pro-actively offer a limited portion of their user data to police.
"They could say 'this person in in Brixton and he sent messages to 40 people and an hour later 25 of them turned up'," said Mr Conradi.
That basic information could be used to narrow down suspects worthy of further investigation, without violating either data protection or RIPA guidelines, he explained.
"There's a specific section in the data protection act which says you can disclose personal information for the purposes of detection of crime without the consent of the person to whom it relates."
The Met Police was unavailable for comment on this matter at the time of writing.