Theresa May, the Home Secretary, will today face questioning by MPs over Government plans to introduce an unprecedented level of surveillance of mobile phones and internet use in what has been derided as a snoopers' charter.
The plans are expected to be announced in the Queen's Speech in May and are likely to include provisions to allow the security services access to every piece of internet traffic in the United Kingdom, on demand.
This would mean that Government agents would be allowed to see what websites people are accessing, and for how long. They would also be able to see who was emailing whom, who was phoning whom, and for how long.
Critics of the plans have argued that they set little store by Government assurances that security services will still have to seek a warrant to gain access to the content of conversations or emails that have been monitored.
Under the plans will be the suggestion that Internet Service Providers (ISPs) will be obliged to install 'black boxes' in their systems which would record all internet traffic and give the Government Communications Head Quarters (GCHQ) access to it on demand.
On top of that, critics also say there is a concern that if the 'black boxes' were introduced they would be costly - ISPs are unlikely to fund them and so they could be Government-owned - leaving them vulnerable to unwarranted 'snooping'.
Mrs May will be cross-examined on these issues by the Home Affairs Select Committee in the Commons and will have to defend policy proposals very similar to those which were roundly condemned by her own party when they were abandoned by the last Labour government.
An analysis of the Government's plans conducted by the London School of Economics (LSE) said: "Private meetings would be a thing of the past. This would be akin to having to notify the Government of all the people you met with last night, in order to give them the opportunity to choose whether they want to retrospectively read any conversation transcripts that may be available. This has profound implications for the ability to associate free from surveillance."
The report added: "Communications Service Providers would be called on to hold all the detailed transaction information of every Member of Parliament and every journalist: their phone calls (to lobbyists, colleagues, constituents and sources); locations; website viewings; social networking and chats. It is a map of everyone's private life, but also his or her professional and social life too."
The intelligence services, MI6, MI5 and GCHQ have lobbied the Government hard for the introduction of legislation which would extend their abilities to monitor the contacts between terrorists, organised criminals, cyber spies and violent groups using the internet and voice systems like Skype to hide their communications.
Director-General of the Office for Security and Counter-Terrorism, Charles Farr, a former MI6 operator, has been at the forefront of driving the idea through Whitehall.
Securocrats insist they need the wide-ranging powers to prevent terrorist attacks, fight paedophile crime and defend the country against cyber criminals. But many MPs remain unconvinced.
They argue that while terrorism is a frightening tactic it does not, and will not, amount to the sort of strategic threat which would require an extension of unfettered surveillance to the level of war-time.
David Davis, the veteran Tory MP, said that the coalition's proposals were a "snoopers charter" which turned Britain into a "nation of suspects".