Police checkpoints have been set up recently in response to the threat posed by dissident republicans
The DUP has reached a deal with Sinn Fein over the devolution of policing and justice powers from Westminster to Northern Ireland. BBC News Online explains the background to what has been called "the final piece of the devolution jigsaw." Why weren't policing and justice powers moved to Northern Ireland when other functions were devolved under the Good Friday Agreement?
Policing and criminal justice were highly contentious matters and a definitive way forward could not be reached at the time.
Many nationalists felt they had not been well-served by the police and wanted radical reform.
Unionists were uneasy at the prospect that those who had attacked the police could be involved in overseeing them.
The Good Friday Agreement, signed in 1998, said the powers would be devolved at some point in the future with the approval of the political parties.
The parties also agreed to the setting up of independent commissions which led to major reforms of the police and criminal justice system.
What is the Sinn Fein position?
Sinn Fein believes these powers should have been devolved long ago.
It wants to be able to say that policing and justice powers are no longer being exercised by a British minister in Westminster.
Department of Justice Bill: From BBC Democracy Live
It was on the understanding that devolution would happen that Sinn Fein dropped its longstanding opposition to the police.
The party thinks devolution would make the justice system more accountable.
In recent months it has criticised the prosecution service in Northern Ireland and called for "root and branch reform."
Will a Sinn Fein member become Justice Minister?
That is not an immediate prospect as the Justice Minister will have to be elected by a cross community vote in the Assembly.
It is likely that the job will go to a member of the cross-community Alliance party.
This cross community provision will lapse in 2012 so there will need to be a fresh agreement at that time.
What is the DUP position?
The DUP is also in favour of the devolution of policing and justice powers but took a more cautious line than Sinn Fein.
The party said it would only assent to devolution of the powers when it was sure that there was broad community confidence in doing so - it has said the deal is the basis of gaining that confidence.
The DUP will face opposition from the hardline Traditional Unionist Voice party which describes the devolution of powers as "part of Sinn Fein's unification strategy."
The role of the Ulster Unionist Party (UUP) will be crucial in providing political cover for the DUP.
The DUP will be hoping the UUP will fully back the deal which would help demonstrate that there is broad community confidence.