The British are the most spied upon people in the democratic world, but only the judiciary can restrain parliament

Lord Thomas Bingham has written the following in The Guardian:-

In times of heightened tension, caused by war, terrorism or other public emergency, ministers tend to exert their powers to the limits of what they believe to be politically acceptable and legally permissible. They are, very properly, concerned to ensure the survival of the nation and the safety of those within its borders. This is their public duty.

The practical test of political acceptability is the obtaining of parliamentary approval. This is not usually a problem, since public opinion is generally supportive of tough repressive measures in time of crisis. Thus, despite a warning by the joint parliamentary committee on human rights, parliament enacted part 4 of the Anti-Terrorism, Crime and Security Act 2001, providing for the indefinite detention without charge or trial of foreign nationals suspected of involvement in terrorism, while making no comparable provision for UK nationals similarly suspected. But there are limits, as evidenced by the government's ill-judged and ill-fated attempts to detain terror suspects for 90, and then 42, days without charge - pills that parliament declined to swallow.

The test of legal permissibility falls to be judged, ultimately, by the courts. But in times of crisis the courts too have tended to be uncritical of the executive. During both world wars judgments were given that would never have been given in quiet times, and the first half of the 20th century has been described as a period of judicial catatonia.

But the judges are also heirs of an older and nobler tradition. This is the tradition that led them to develop the remedy of habeas corpus, the most potent safeguard against executive tyranny the world has devised. It led them to develop a range of other remedies to control executive lawlessness, still best known by their old Latin names such as certiorari and mandamus. They are not, as David Blunkett surprisingly thought, "a modern invention ... substantially in being from the early 1980s". It is this tradition in which judges in 1765, for instance, struck down general search warrants issued by the executive.

READ MORE at:-
http://www.guardian.co.uk/commentisfree/2009/feb/17/surveillance-civil-liberties