IF Sinn Fein and the loyalists' fringe parties gain places at the opening session of all party negotiations on June 10th, they will be enabled between them - and even without the likely support of the SDLP - effectively to counter the UUP's demand that some actual arms decommissioning should take place before substantive issues are addressed.
The ground rules for negotiations, already published by the British government, make it clear that, on any disputed matters, "sufficient consensus" must be achieved among the parties to allow negotiations to proceed.
The rules for establishing sufficient consensus must be agreed in advance of negotiations. But the British ground rules make it plain that any departure from the rule of unanimity must be "within minimal limits".
They also say that, in all cases, any decision taken must be supported by "a clear majority, in both the unionist and nationalist communities in Northern Ireland".
Although clearly defined and binding procedural rules for the negotiations have yet to be decided - and are, in fact, at the heart of the ongoing differences between the British and Irish governments - the ground rules already presented to the British Parliament by the Northern Secretary, Sir Patrick Mayhew, would prevent any single party such as the UUP imposing conditions on progress.
Last week, the UUP leader, Mr David Trimble, said that substantive matters would not be addressed unless some equipment had actually been handed over by paramilitaries as concrete evidence that they were honouring the Mitchell Principles.
He asserted, in effect, that Sinn Fein and the loyalist fringe parties would automatically exclude themselves" from the negotiations if they failed to do that.
Mr Trimble also threatened that if anyone tried to raise the constitutional position of Northern Ireland for discussion, the UUP would "take that issue off the table".
However, the published ground rules plainly deny the UUP or any other participant the power to impose such conditions. If no consensus was reached on such demands, the only obvious recourse open to Mr Trimble would be to withdraw from the negotiations. Last week, however, he ruled out this option, saying: "If you withdraw, you are leaving other people there in possession of the field."
Sinn Fein, the loyalist fringe parties, and the SDLP would all certainly oppose the imposition of rigid requirements concerning prior decommissioning as a precondition for addressing other issues. This would make it impossible to secure "sufficient consensus" within "minimal limits" for the negotiations to proceed.
Thus Mr Trimble's demands amount to an attempt to define and constrain the nature of the negotiations in advance of any discussion. The ground rules in the British government's Command Paper show that he has no legal means of enforcing such requirements. If the UUP, once it has entered the opening session, attempts to impose its own conditions and interpretations, it can be overruled by a clear consensus among the other participants.
It is already evident, however, that the primary hurdles to be overcome by the talks concern their own detailed rules of procedure and agenda. The entire exercise is likely to founder on the definition of these practical working rules and arrangements well before the decommissioning issued comes to the fore.
The opening plenary session will have to "adopt, and commit the participants to negotiate, a comprehensive agenda which reassurance, both in terms of addressing the report of the International Body and ensuring that a meaningful and inclusive process of negotiations is genuinely being offered".
The agenda is to include "all the significant items which the various negotiating teams consider relevant and which will, therefore, have to be addressed in the search for agreement".
Conceivably, when the question of the agenda comes up, Sinn Fein or the SDLP will take the opportunity of seeking to place on it the Government of Ireland Act 1920. The unionists will object, and a procedure must then be adopted to resolve this impasse.
Agreement on procedures must therefore be sought, and minutely defined, even before an agenda for discussion can be constructed.
In this regard, a vital role will devolve upon another aspect of the negotiations which has scarcely received attention. The ground rules provide for the establishment of a "business committee" - separate to the plenary sessions - to co ordinate the progress and the procedures of the negotiations.
The business committee "would not deal with the substance of the negotiations but would address unresolved procedural issues. It could also determine the modalities for dealing with any issue which does not fall exclusively within any of the three strands".
On the face of it, this committee will have a much more crucial task than the negotiating sessions.
The problem is, however, that an intractable wrangle is more than likely to arise over the very procedures by which this procedural committee is to be established.