Belfast High Court will today hear a legal challenge from Ms Michelle Williamson to Dr Mo Mowlam's ruling that the Provisional IRA ceasefire is intact.
Ms Williamson, whose parents were killed in the Shankill bombing, was last month granted permission to seek a judicial review.
The hearing is expected to last several days and will centre on the terms of the Northern Ireland (Sentences) Act 1998, which deals with the early release of paramilitary prisoners under the terms of the Belfast Agreement.
The scheme is linked to the paramilitary groups observing a proper ceasefire. Ms Williamson's lawyers may seek to subpoena Dr Mowlam and the RUC Chief Constable, Sir Ronnie Flanagan, to give evidence. The case is being supported by the Ulster Unionist Party, although Ms Williamson has stressed that her action is being taken personally.
Under the Northern Ireland (Sentences) Act 1998, the Northern Secretary is required to take into account whether a paramilitary group is committed to democratic and peaceful means, has ceased to be involved in acts of violence, does not promote or direct acts of violence, and is fully co-operating with the decommissioning process.