The Conservatives say the current law is confused

Patrick Mercer's Criminal Law (Householder Protection) Bill received a second reading by 130 votes to four, after Tory MPs packed the chamber.

Mr Mercer's plan would mean people would be prosecuted only if they used "grossly disproportionate force".

But ministers say the measure is unnecessary and are likely to block it.

Risky business

Mr Mercer's Bill would change the current test of "reasonable force" and clear up "chaos and confusion" over the issue, he said.

A test of "grossly disproportionate" force would make householders more confident about their rights and burglars less confident about entering homes.

It is a rare and frightening prospect to be confronted by an intruder in your own home Use of Force guidance Read new government advice Download the reader here

He argued: "There would be less burglaries and less opportunities for bloody confrontations."

Home Secretary Charles Clarke has already said the definition will not be changed.

But Labour former minister Frank Field backed the Bill and warned that ministers were only opposing the move so that they could further clarify the law before the election and take credit for it.

Shadow home secretary David Davis added his support for the measure, stressing: "At the moment the burglar feels less at risk than the homeowner, but the Bill will change that."

But Home Office Minister Paul Goggins said changing the law was unnecessary because it currently struck a fair balance.

Vigilantes

"The law is on the side of householders," he said. "Being burgled is a very frightening experience and householders who react instinctively and attack intruders will only be prosecuted if they use very excessive force.

"It is only in the most extreme circumstances that householders are prosecuted for violence against burglars.

"What the law does no permit is an act of retaliation.

"Punishment of criminals is rightly a matter for the courts. It is not for victims, vigilantes or anyone else to take the law into their own hands."

The debate was reignited by recently retired Metropolitan Police Commissioner Lord Stevens who said individuals should be allowed to use what force was necessary against an intruder.

Ken Macdonald, Director of Public Prosecutions, tried to clarify the matter by saying householders could kill burglars and not face prosecution if "reasonable force" was used.