LONDON, England - May 19, 2010 - Defying those who said it might be paralyzed by internal divisions, Britain’s new coalition government of Conservatives and Liberal Democrats on Wednesday unveiled the most ambitious plan in decades for upending the highly centralized and often intrusive way the country is governed.

The plan, as laid out by the deputy prime minister, Nick Clegg, would roll back a proliferation of “nanny state” laws, non-elected administrative bodies and surveillance systems - many of them a product of Labour’s 13 years in power - that critics say have curbed individual freedoms and enlarged state powers to a degree unrivaled by most other democratic societies.

Vowing that the coalition would end “the culture of spying on its citizens,” Mr. Clegg said it would “tear through the statute book,” scrapping a nationwide system of identity cards on which the Labour government spent huge sums, and abandoning a new generation of “biometric” passports that would hold a vastly expanded archive of personal data. In addition, he said, there would be new restrictions on the government’s right to intercept and hold personal Internet and e-mail traffic and to store DNA data from people not convicted of any crime.

Mr. Clegg said the changes would also place new curbs on tens of thousands of closed-circuit television cameras in public places - a field in which, critics say, Britain is a world leader. Those critics, have complained that despite the cameras - which the police use to trace the movement of suspects and victims through shopping centers, city streets, hospitals, gas stations and other public places - there has been little impact on crime rates over the years.

“It is outrageous that decent, law-abiding citizens get treated as if they have got something to hide,” Mr. Clegg said.

The plan would also create a fully elected House of Lords, scrapping heredity and political favor as a passport to power, and commit to a referendum on changing the voting system for the House of Commons. Under the proposed “alternative vote” system, candidates would have to gain 50% or more of the vote in their constituencies to secure election, effectively shaking up the politics of “safe” parliamentary seats that has given many M.P.’s what amounts to lifetime employment.

In addition, the plan would adopt an American-style power of recall, opening the way for restive voters to unseat errant lawmakers by gathering 10,000 signatures on a petition, and introduce new laws to regulate Britain’s $3.5-billion-a-year political lobbying industry. It would also set a five-year “fixed term” for parliaments, coupled with a new law requiring the votes of at least 55% of M.P.’s to topple the government, instead of a simple majority as at present. That measure is intended, the coalition has said, to discourage political parties from forcing elections for purely partisan reasons.

Libel laws that strongly favor litigants seeking to shield private and professional activities from news media scrutiny will also be changed, Mr. Clegg said. In recent years, London has been dubbed the “libel capital of the world” for the habit of wealthy people, including movie stars and business tycoons, of filing defamation suits in British courts that tend to favor privacy rights over press freedoms.

The changes would decentralize much of the power now wielded by the government in London, which Mr. Clegg said made Britain “on some measures, the most centralized country in Europe, bar Malta.” He said the coalition would abandon the Labour conviction that “change in our society must be forced from the center,” and allow communities much greater say in the management of hospitals, schools, local police forces and other matters. “We’re not insecure about relinquishing control,” he said.

Over all, Mr. Clegg billed the overhaul package as the “most significant program of empowerment by a British government” since the Great Reform Act of 1832, which extended the franchise beyond the landed classes. It was, he said, nothing less than “a power revolution,” and “a fundamental resettlement of the relationship between state and citizen that puts you in charge.”

The new program immediately met opposition from critics who called it risky and overdrawn, as well as a smokescreen to disguise issues on which the Conservatives and Liberal Democrats, as coalition partners, have wide differences. Even supporters said it could take years to put in place, assuming it could overcome opposition from a political establishment accustomed to largely untrammeled executive power.

A foretaste of the opposition came from Alan Johnson, who until the fall of the Labour government last week was home secretary, with wide powers over security, the police and other regulatory agencies. Mr. Johnson accused Mr. Clegg of employing “rampant hyperbole” on the surveillance issue and said that Labour’s law-and-order changes, at the heart of Mr. Clegg’s assault, had wide public backing.

But supporters hailed Mr. Clegg’s speech for challenging what has been an article of faith in many quarters throughout modern history: that Britain, with its historical claim as the “mother of democracy,” has remained an example for much of the rest of the world to envy. For much of the last 200 years, a British prime minister backed by a loyal parliamentary majority, and freed from the constraints of a written constitution, has had powers that American presidents and other rulers could only envy.

Mr. Clegg said the government knew it would meet with widespread skepticism. “All politicians say they want to give people more control over their lives,” he said, but added, “This government is going to make it happen.”

Whether that is possible, though, may depend on whether the coalition can hold together in the face of strong pressures from within each of the two coalition parties, including a Conservative right wing that is likely to be deeply discomfited by wide-ranging political changes.

But another view holds that David Cameron, the Conservative prime minister, has seized on the coalition as an opportunity not only to change Britain, but also the Conservative Party. In effect, some commentators have said, the pact with the Liberal Democrats has freed Mr. Cameron to govern in ways suited to his own liberal predilections, and his vow to make the Conservatives more compassionate.