David Cameron
© David Moir/Reuters
British plans to extend the state's powers to monitor emails and other social media, and set up secret courts to hear evidence gathered by intelligence agencies, are threatening to destroy the country's ruling coalition.

When the Queen reads an annual agenda-setting speech to parliament on May 9, the Conservative-Liberal Democrat coalition of Prime Minister David Cameron is expected to unveil sweeping legal reforms to give police and security forces the power to monitor all digital communications and establish special courts that can review top secret intelligence information.

But before the new laws have even been introduced they have ignited a storm of controversy with back-bench Conservative MPs and Liberal Democrat leaders both warning of a potential invasion of privacy and attacks on individual legal rights.

Government spokesmen insist: "It is vital that police and security services are able to obtain communications data in certain circumstances to investigate serious crime and terrorism and to protect the public."

They also say special secret trials are needed to handle sensitive intelligence material.

In the past, British prosecutors have had to withdraw from trials because they were unable to back-up their cases without publicly exposing secret intelligence. The British government is proposing to establish special courts for civil trials and inquests to hear secret evidence. Under the plan, claimants and their lawyers will be shut out of the hearings, but will be represented by special, security-cleared, advocates.

Under pressure from his own party, Deputy Prime Minister Nick Clegg, the Liberal Democrat leader, has written a letter to fellow cabinet ministers on the National Security Council warning them the security services "cannot be allowed to ride roughshod over the principle of open justice."

He has also invited civil liberties groups to challenge proposals to expand police surveillance powers, saying any legislation must be carefully scrutinized to get a proper balance between security and liberty.

When Britain's previous Labour government tried to introduce similar legislation to expand security surveillance powers in 2009, it rapidly withdrew the laws after facing the teeth of a fierce public backlash.

Now, Liberal Democrats are threatening to lead opposition to the new laws.

"There must be no question of the authorities having universal Internet surveillance powers," Liberal Democrat President Tim Farron wrote recently on his party's website. "We should be prepared to look at what will now be draft legislation with an open mind, but we should be prepared to put our foot down and pull the plug if we consider the proposals too illiberal."