The bill to track everyone's email, Facebook, text and internet use has proved to be one of the most controversial within the coalition and has been slow-streamed in the government's legislative timetable after last-minute coalition talks.
The measure, which has been criticised by civil liberty campaigners as a "snooper's charter", has been taken out of a more general Home Office- and Ministry of Justice-sponsored crime and courts bill, which ministers need to get on to the statute book as fast as possible.
The decision to have a stand-alone bill follows Nick Clegg's insistence that it must be accompanied by the "strongest possible safeguards". These are expected to include oversight on a case-by-case basis by a surveillance commissioner, a review of existing measures to protect the security of everyone's data, and the publication of a privacy-impact statement.
Clegg has also promised that the internet-tracking proposal will not be "rammed through parliament", and that open parliamentary hearings will be held to examine draft clauses of the legislation. The proposal has also attracted sharp criticism from the Tory libertarian right, with the former shadow home secretary David Davis calling it an "unnecessary extension of the ability of the state to snoop on ordinary people".
The measure is expected to require internet service providers to retain and store for 12 months the 25% of "traffic data"? who sent an email, to whom, from where and at what time ? that they currently do not keep for their own commercial billing purposes. Overseas-based internet companies, including Gmail and Hotmail, are currently excluded from the legal requirement to keep billing data for 12 months.
Security and police chiefs say such communications data has played a significant role in every major security service counter-terrorist investigation in the past decade. But the rapidly changing nature of internet use means that they can no longer track communications between terrorist or criminal suspects.
The monitoring data will be available to the police and security services only in "real time", in cases involving active terrorist plots, and in hostage or kidnapping situations where lives are at risk.
The bill will restrict access to the most sensitive types of data to the police, emergency services and intelligence agencies. However, local authorities, which were responsible for 1,800 out of the 500,000 requests for such data last year, will need the approval of a magistrate in future for such requests.
The separate crime and courts bill will set up the National Crime Agency from next April, speed up immigration appeals and strengthen the powers of UK Border Force officers.
It will also include proposals to introduce television cameras into courts, reform judicial appointments and allow magistrates sitting on their own to operate from community centres and police stations so that they can deal with low-level, uncontested cases within days or even hours of a suspect's arrest.