Justice Secretary Ken Clarke has said a householder who knifes a burglar will not have committed a criminal offence under plans to clarify the law on self-defence in England.
He told the BBC people were entitled to use "whatever force necessary" to protect themselves and their homes.
David Cameron recently said the issue should be put "beyond doubt".
Labour said the law was "already clear" and the remarks were a "smokescreen" to hide confusion over sentencing changes.
Mr Clarke has come under attack over proposed changes to sentencing policy, but has denied making a series of U-turns on key elements amid pressure from Tory MPs and sections of the media.
He has said he is committed to axing indeterminate prison sentences, despite opposition from many Tory MPs.
He said indeterminate sentences - where prisoners can be held beyond their original release date if they still pose a danger to society - had been an "unmitigated disaster" since they had been introduced by Tony Blair and suggested an alternative to them would be in place within two years.
On people's rights to self-defence in their homes, Mr Clarke said there was "constant doubt" about the issue and the proposed legislation would make this "much clearer".
Under the terms of the 2008 Criminal Justice and Immigration Act, homeowners who use "reasonable force" to protect themselves against intruders should not be prosecuted, providing they use no more force than is absolutely necessary.
But the government is set to place people's right to defend their property, long present in common law, in statute law.
"It's quite obvious that people are entitled to use whatever force is necessary to protect themselves and their homes," Mr Clarke said.
Asked about what this would mean in practice, he said: "If an old lady finds she's got an 18 year old burgling her house and she picks up a kitchen knife and sticks it in him she has not committed a criminal offence and we will make that clear."
He added: "We will make it quite clear you can hit the burglar with the poker if he's in the house and you have a perfect defence when you do so."
Mr Clarke said legal protection would not extend to anyone shooting a burglar in the back when they were fleeing or "getting their friends together to beat them up".
"We all know what we mean when we say a person has an absolute right to defend themselves and their home and reasonable force.
"Nobody should prosecute and nobody should ever convict anybody who takes those steps."
But Labour said ministers had created confusion by first suggesting they were going to change existing laws before deciding merely to clarify them.
"The law is already clear - under the existing law people can rightly defend themselves and their property with reasonable force," said shadow justice secretary Sadiq Khan.
He added: "This government has used spin and smokescreens of new laws in an attempt to distract from what is a justice bill in total shambles."
Mr Clarke has been defending proposed sentencing and legal aid changes in Parliament.
Although no plans to change indeterminate public protection sentences are currently included in proposed legislation debated on Thursday, Mr Clarke earlier made clear his determination to repeal them.
While some people had to stay in prison for an unspecified amount of time, he said the six-year old policy was "filling up" prisons and it was "indefensible" some prisoners did not know how long they would have to serve.
Ministers dropped plans to offer suspects pleading guilty at the earliest opportunity a 50% reduction in their jail sentences following a public consultation, but Mr Clarke suggested there would be no backtracking on this matter.
Although he would consider carefully any changes, he said more prisoners should get "fixed-length" sentences.
Tory MP Philip Davies said indeterminate sentences - 6,000 of which have been handed down - have reduced crime and Mr Clarke's stance on the issue "shows beyond all doubt that re-offending is not his priority".
"This bill is not the rehabilitation revolution or the reduced reoffending revolution we were promised," Mr Davies told the Commons.
"This is a release revolution which will simply catapult more criminals out on to the streets to commit more crimes."
A No 10 spokesman said the government was looking at the system of indeterminate sentencing "with a view to replacing it".
Legal advice centres
MPs also discussed the government's plans to cut legal aid in England and Wales at the second reading of Legal Aid, Sentencing and Punishment of Offenders Bill.
Under the plans, aimed at saving £300m from the £2.1bn legal aid bill, people will not be eligible for legal aid in a far broader range of civil cases than at present.
But the proposals have come under fire from lawyers and campaign groups, who claim they will lead to more crime and penalise victims.
In an effort to reassure some critics, Mr Clarke announced an additional £20m for this financial year to help fund not-for-profit legal advice centres.
"I agree that they do very important work in providing quality, worthwhile advice of the kind required by very many people who should not need adversarial lawyers," he said.
But he added that legal aid was only one of several income streams for many such organisations, with 85% of Citizens Advice Bureaux funding coming from other sources.
At the end of the debate, 295 MPs voted in favour of the bill and 212 voted against. Five Conservatives were among those who voted no.