At first sight, policing looks to be one of the few loose-ends left dangling from the package that the Northern Ireland politicians agreed on Good Friday. Independent commissions of the sort which Chris Patten will head (if the referendum produces a Yes vote) are usually appointed only where a political problem is judged so insoluble that to wrestle with it at that particular juncture would be to jeopardise the possibility of rational political movement elsewhere.

That seems superficially to have been the case in respect of policing and the Belfast talks, and it is indeed true that arguments over the future of the RUC at times threatened to collapse the whole process.

Despite this, the idea that the entire question of policing has been put on some very long finger to await the fresh verdict of Patten and his fellow commissioners is largely illusory. In fact the multi-party talks made enormous strides on policing. What was agreed on Good Friday falls full-square within a deeper momentum towards changing the RUC which is quite independent of the peace process itself, and which will occur whether or not the referendum supports the accords.

Patten and his independent commissioners will start not with a blank page but with a book replete with clear instructions.

As early as the Framework Documents, the British Government of John Major declared itself "open to the consideration of proposals designed to enhance the extent to which the community at large in Northern Ireland can identify with and give full support to the police service."

The pace of the pressure for change quickened with the IRA ceasefires, and became intense with the arrival of the new Labour administration in May 1997. Even the supposedly "unionist" heads of agreement concluded between the British and Irish governments in January this year promised "effective and practical measures to establish and consolidate an acceptable peaceful society, dealing with issues such as . . . policing . . .".

The acceptance by rational unionism of the inevitability of police reform is evident from what was agreed on Good Friday. The participants declared that the agreement "provides the opportunity for a new beginning to policing in Northern Ireland with a police service capable of attracting and sustaining support from the community as a whole."

The "unique opportunity" provided by the accords was "to bring about a new political dispensation which will recognise the full and equal legitimacy and worth of the identities, senses of allegiance and ethos of all sections of the community in Northern Ireland"; this was what should "inform and underpin the development of a police service representative in terms of the makeup of the community as a whole and which, in a peaceful environment, should be routinely unarmed."

The Patten Commission is instructed by the Belfast Agreement to bear all this in mind. Its proposals will also have to be "designed to ensure that policing arrangements, including composition, recruitment, training, culture, ethos and symbols, are such that in a new approach, Northern Ireland has a police service that can enjoy widespread support from, and is seen as an integral part of, the community as a whole".

In all probability David Trimble and his colleagues found all this easier to accept because it was likely to happen anyway, whether or not their party judged it right to collapse the talks on the basis of its unacceptability. The Unionist Achilles heel - disguised until May 1st last year by the weakness of the Major government - has always been its vulnerability as a tiny UK faction to the exercise of political power by the government, appointed by the very monarch to whom their ideology requires them to say that their loyalty is unswerving.

The Blair administration's Police (Northern Ireland) Bill, currently going through parliament, is a neat reminder of this, to concentrate Unionist minds. The Bill establishes a new position of Police Ombudsman, creates a new Northern Ireland police service (of which the RUC is to be a mere part) and dispenses with the old declaration of office made by constables in favour of a new cross-community affirmation. More could follow from this sovereign source, whatever the result of the vote on May 22nd.

If the outcome of the Commission's investigations is so clear, why bother with a Commission? This is where the analogy between Patten and Senator Mitchell becomes almost exact.

Mitchell started with an even longer brief from the governments: the framework documents and all that went with them. His job was to facilitate an open-ended interaction between the parties which both allowed debate and, at the same time familiarised Northern Ireland's political leadership with the language it was essential for them not only to adopt, but to internalise, if a solution was to be forthcoming. In this task he succeeded brilliantly.

The loose end which Patten must address is not the substance of policing reform but the failure of some parties to the Belfast Agreement fully to appreciate the value of the language of community acceptability that they have allowed themselves to agree.

Policing reform is not a nationalist trick aimed at destroying law and order for good; it is a way of guaranteeing that order. Nationalist mistrust of the RUC is not some irrational misperception; it is a communal response made inevitable by past events and by unionism's habit of treating the officers of the RUC as their community's private protectors. It will take time to change these essentially unionist attitudes, since little was done by way of preparation before the Belfast Agreement.

It will also take a little while for the RUC to appreciate that the future offers opportunities as well as inevitable structural change. The Patten Commission buys the time, and Mr Patten will no doubt use it to foster the trust upon which policing reform (and indeed the entire process itself) will inevitably depend.

The point is not whether the new Northern Ireland police force will or will not call itself "royal"; nor is it whether this or that flag will be flown on this or that occasion. Anxiety about such matters is a consequence, not a cause, of sectarian mistrust. Patten will have to deal with them.

It is to be hoped that their essential triviality will be recognised across the political spectrum and that the inevitability of change on some or all of these matters will not be turned into the acid test of the acceptability of what is, after all, part of a much greater project: the achievement of peace with justice in Northern Ireland.

Conor Gearty is Professor of Human Rights Law, King's College London