Rulings by the European court of human rights (ECHR) would no longer be enforceable in the UK under radical plans by the Conservatives.

Under proposals to be included in the party’s general election manifesto, the Tories would reverse more than half a century’s tradition of human rights authority residing in Europe by giving parliament the right to veto judgments. The authority of the court in Strasbourg would be severely curtailed, with parliament given the final say in deciding whether or not to adopt ECHR decisions.

A document setting out the plans promised to “restore sovereignty to Westminster” through a parliamentary override that would prevent politically unacceptable Strasbourg rulings being enforced in UK law. The far-reaching changes would enable a future Tory government to limit human rights to only the “most serious cases”, deport more “terrorists and serious foreign criminals” and defy policies such as the ECHR’s requirement that some prisoners be given a vote.

Opponents warned that what would in effect be a judicial opt-out risks unravelling the rule of human rights law across Europe at a time when Russia and other nations are chafing against the enforcement of ECHR decisions.

The plans are contained in an eight-page strategy paper, entitled Protecting Human Rights in the UK, published by Chris Grayling, the justice secretary. “We can no longer tolerate this mission creep,” he said. “What we have effectively got is a legal blank cheque, where the court can go where it chooses to go. We will put in place a provision that will say that the rulings of Strasbourg will not have legal effect in the UK without the consent of parliament. Effectively, what we are doing is turning Strasbourg into an advisory body.”

Dominic Grieve, the former attorney general who was removed at the last reshuffle, told the Guardian the proposals were “almost puerile”. He added: “I also think they are unworkable and will damage the UK’s international reputation.”

The strategy paper pledges that Britain should remain signed up to the European convention on human rights, the principles that guide the court. By doing so they avoid an immediate diplomatic crisis, but there is a clear threat of withdrawal if no agreement is reached with the Council of Europe, the 47-member nation body that oversees the Strasbourg court.

The text of the original convention will be written into UK law and UK courts will no longer be required to “take into account” Strasbourg decisions. Germany’s constitution, it claims, does not require ECHR judgments to be adopted.

The impact would be wide-ranging. The UK armed forces would cease to be subject to human rights legislation overseas, and Labour’s 1998 Human Rights Act would be scrapped to be replaced by a “British bill of rights and responsibilities”, the policy document states.

Civil liberties groups reacted with alarm to the plans, which Grayling mentioned briefly in his speech to the party conference earlier this week and David Cameron also referred to. Critics suggested that the precise details had been held back to avoid an internal row over human rights spoiling the appearance of party unity at the conference.

Grayling said: “We cannot go on with a situation where crucial decisions about how this country is run and how we protect our citizens are taken by the ECHR and not by our parliament and our own courts. We also have to be much clearer about when human rights laws should be used, and that rights have to be balanced with responsibilities. People in this country are fed up with human rights being used as an excuse for unacceptable behaviour. We will always stand against real human rights abuses and political persecution. But these plans will make sure that we put Britain first and restore common sense to human rights in this country.”

A draft consultative bill of rights and responsibilities is due to be published before Christmas. One of its targets is what it says is misinterpretation of article 8 of the convention, which guarantees a right to family life – the subject of repeated tabloid attacks. “For example,” the strategy paper says, “a foreign national who takes the life of another person will not be able to use a defence based on article 8 to prevent the state deporting them after they have served their sentence.”

But Grieve said: “The suggestion that they can be negotiated with the Council of Europe so that the UK has its own space where it can [take what it wants] while everyone else complies is almost laughable. How can the UK obtain such a status when other countries have signed up to an agreement collectively to implement judgments?” Some ECHR judgments, such as the right to give prisoners the vote, were, he said, mistaken, but the proposals in the Conservative document seemed to “lack any maturity”.

They also drew a furious response from the Tories’ coalition partners. Simon Hughes, the Liberal Democrat justice minister, said: “The Conservatives don’t care about the rights of British citizens – they care about losing to Ukip. These plans make no sense: you can’t protect the human rights of Brits and pull out of the system that protects them.

“Europe’s human rights laws were designed by British lawyers to reflect British values of justice, tolerance and decency. We will not allow the Tories to take away the hard-won human rights of British people when in the UK or anywhere else in Europe.”

Andrea Coomber, director of the civil rights group Justice, said: “Conservative party policy now says: ‘We support minimum human rights standards, but only if we define their content.’ A patchwork of national rules would mean no standard at all; every human being, subject only to the whims of national interest. This vision would reset the clock to 1945, before Eleanor Roosevelt, Churchill and Maxwell-Fyfe ever put pen to paper.”

Sadiq Khan, the shadow justice secretary, said: “Once again David Cameron is pandering to Ukip instead of standing up for the rights and best interests of the people of Britain. The truth is that our courts have been free to interpret rulings by the European convention on human rights for 50 years – the Human Rights Act did nothing to change that fact.

“The ECHR does need reform, which is why Labour has called for Strasbourg to do more to improve the quality of its judges and apply the ‘margin of appreciation’, giving member states the wriggle room to interpret decisions appropriately.”

Landmark human rights judgments

• Ireland v UK. ECHR ruled that the British army’s use of five techniques on detainees amounted to inhuman and degrading treatment.

• Dudgeon v UK. ECHR’s 1981 ruling that criminalisation of homosexuality in Northern Ireland was illegal.

• Hirst v UK. ECHR ruling in 2005 granting some prisoners voting rights.

• In 2010 a Kurdish asylum seeker who caused the death of a 12-year-old girl in a driving accident avoided deportation. Tabloids blamed the fact that he claimed right to a family life, enshrined in the convention.

• Al Jedda and Al Skeini v UK. ECHR said in 2011 those detained in Iraq by UK were subject to its jurisdiction.

• Smith and others v Ministry of Defence. Treatment of detainees. A 2013 UK supreme court decision which found that, through human rights legislation, the army has a duty of care to soldiers killed in combat. Case brought by families of soldiers who died in Snatch Land Rovers.