Legislation allowing fugitives from Northern Ireland to return home has been published.
People suspected of being involved in terrorism could return
The proposals cover up to 150 people wanted for crimes committed before the Good Friday Agreement in 1998.
They would have their cases heard by a special tribunal, and if found guilty would be freed on licence without having to go to jail.
Unionists and terrorist victims have already expressed their outrage at this law, calling it an effective amnesty.
The DUP brought relatives of terrorism victims to Westminster to lobby against the scheme.
Between 40 and 150 fugitives could benefit from the scheme, including the former Sinn Fein publicity director Rita O'Hare and the IRA Maze escapee Pol Brennan.
The government and Sinn Fein argue that it clears up "an anomaly" left by the release of those already in jail after the Good Friday Agreement.
The law sets up a two stage process. First someone who will be known as the certification officer will decide if someone is eligible for the scheme.
This could be a paramilitary on-the-run, someone living in Northern Ireland who is charged with an offence before 1998 or a member of the security forces accused of an offence committed when they were combating terrorism.
The case would then go to a special tribunal, consisting of a retired judge sitting without a jury. The tribunal would have all the normal powers of the Crown court but accused would not have to appear for their trial.
If found guilty they would get a criminal record but would be freed on licence. They would have to provide fingerprints and DNA samples to be granted their licence.
The scheme will be temporary but a precise cut off period is not specified in the bill - instead its expiry is linked to the lifetime of the chief constable's historic cases review team, which is looking at unsolved murders during the Troubles.
The measures are contained in the Northern Ireland Offences Bill which is expected to get a rough ride as it makes its way through parliament.
In a statement, NIO minister David Hanson said: "Sometimes it is necessary to make difficult decisions in the interests of entrenching the benefits of peace. This is one such occasion.
"We want to close the door on Northern Ireland's past of violence and paramilitarism, and this legislation is one step in that effort."
Aileen Quinton, who lost her mother Alberta in the 1987 Enniskillen bombing, said the families wanted justice.
She is in London with other victims' relatives to lobby against the legislation.
"Some things are so important that you just have to do them," she said.
"We are not looking for vengeance, we are not looking for sympathy, we are looking for justice and justice has to be the bedrock of any kind of peaceful or decent society."
Chief Constable Sir Hugh Orde said serving and former members of the security forces would be unhappy at being included in the bill.
"I do not anticipate it will be a popular piece of legislation," he told the Northern Ireland Affairs Select Committee at the House of Commons.
"Many of my officers will feel this is not right. I know many soldiers will feel this is not right.
"We need to absolutely clear that the overwhelming majority of police officers and soldiers did nothing unlawful throughout the Troubles."
SDLP leader Mark Durkan told the Commons the proposals represented "collusion on the past" by Sinn Fein and the state.
He asked the prime minister if he accepted "that victims, including victims of state collusion, will not only be deprived of justice, they will be denied the truth".
UUP leader Sir Reg Empey said the on-the-run proposal was "ill thought-out, completely unnecessary and an insult to the victims of terrorism".
"The prime minister is guilty of sending out completely mixed messages," he said.
"On the one hand he is proposing an effective amnesty for some of the most barbaric terrorists in this part of the UK, on the other he proposes tough new laws for terrorists and terrorist related activity on the mainland."
DUP deputy leader Peter Robinson said it was "almost impossible" to find the words to describe the "disgust and revulsion that the vast majority of people in Northern Ireland of all political persuasion will have" at the proposals.
"This abuse of the British justice system is an affront to all innocent victims of terrorist violence," he said.
Alliance leader David Ford accused the government of "coming down against the rule of law" in Northern Ireland.
"In drawing up this grotesque legislation, the government has completely failed to listen to the law-abiding citizens of Northern Ireland on this issue.
"This is a direct follow-on from a side deal struck between the prime minister and Sinn Fein four years ago, completely ignoring the other interested parties, not least the victims."
However, Sinn Fein MP Martin McGuinness said many people had been on-the-run since internment more than 30 years ago.
He said while many people had suffered pain, the legislation was "a sensible measure".
"What is the sense of people being pursued whenever everybody knows that as a result of the releases under the Good Friday Agreement they are not going to spend one day in prison."
On Tuesday, Northern Ireland Secretary Peter Hain said security force members should receive equal treatment.
He said those in the services who found themselves charged with crimes committed before 1998 should not be discriminated against compared to paramilitaries.