It is usually artists who bring a social conscience into museums, albeit one nailed to the wall. Harried directors, on the other hand, who spend their time riding the rapids fed by funding problems, gregarious patrons, prickly professionals, and probing reporters, usually have to make time to think about anything beyond survival. Which explains why the British Museum's recent moves to serve not only an expository or commercial purpose, but a moral one, has taken centre stage in the art world.

As students during the 1960s, many of us demanded that universities divest themselves of the stock of companies profiting from war or apartheid. Today members of that same generation hold the reins at leading organisations, but have largely followed the oft-repeated dictum of Francois Guisot (1787-1874) "Not to be a republican at 20 is proof of want of heart; to be one at 30 is proof of want of head".

While many lacked then (and still do now), that heart – an impulse to shape policies by means of an ethical compass – a few individuals stand out from the pack. Neil MacGregor's recent global-minded initiatives at the British Museum, including sending a keeper to war-torn Baghdad, and developing peer-to-peer programmes with museums in Africa and Asia, are best understood as. part of a larger generational impulse to map leadership to suprainstitutional concerns.

The origins of such conscience-led behaviour are varied, and ultimately less significant than the results of such behaviour. The UK's Department for Culture, Media and Sport (DCMS), like the Institute of Museum and Library Services (IMLS) in the US, has sought over the last few years to track organisational achievements in social engineering, looking for the "instrumental" effects of museum programmes and activities, rather than assessing the "intrinsic" value of collecting, preserving, and interpreting museum objects. The policy of grading instrumental activities in this notoriously hard-to-measure sector made an easy transition from Reaganera appointed arts officials all the way to those of the current administration, and will doubtless survive the end of the Blair government as well. Mr. MacGregor's initiatives to find a new way forward for the BM as an instrumental organisation is both pragmatic – a reaction to growing calls for "repatriating" treasures – and principled.

One director can reshape the course of all museums. Thomas Hoving [former director of the Metropolitan Museum] catapulted museums from research-focused organisations into commercial tourist attractions, leading inexorably to the current Tut extravaganza, a co-option of museum authority by the powerful axis of AEG Exhibitions, and Arts and Exhibitions International, and National Geographic.

Mr. MacGregor's predecessor, Robert Anderson, was early on troubled by the amorality of the British Museum's acquisitions policy, and helped set an important debate in motion about how cautious museums need to be in policing prospective acquisitions. Mr. MacGregor's stance is bold because, somewhat hubristically, it bucks the commercialising trend of the US, opting instead to use an ethical compass in decisions about acquisitions and loans. Formal evidence of this new direction came by means of the 26 March 2004 adoption of new BM guidelines for collecting antiquities, according to which: "Wherever possible the Trustees will only acquire those objects that have documentation to show that they were exported from their country of origin before 1970, and this policy will apply to all objects of major importance."

The British Museum's policy is noteworthy because museums had up until then argued that the absence of proof of illegal export provided adequate protection in making acquisitions. His trustees have now put the onus on the museum to acquire only documented exports. Peer institutions in other Western countries were startled by this unequivocal posture, and are coping with its aftershocks over a year later.

What could explain the shift to an ethically-governed British Museum beyond a generational change in leadership? Can the divide be attributed in part to the fact that European museums have survived the loss of Empire, and are seeking to guard their spoils--Elgin Marbles included-with scientific rigour? While the United States is only now warming up its imperial ambitions, and reserving the right to claim moral ascendancy over art-rich source countries with inadequate measures to protect their past?

This would be a simplistic formulation. Neil MacGregor's efforts are well timed, coming as they do in the face of mounting public pressure to "return" ancient treasures to modern nation-states built on the soil high above long-lost civilisations. But however exploratory and expedient MacGregor's initiatives may feel, they bear the mark of principle. Most North American museum directors operate in an individualistic, grow-ordie gladiatorial arena, whereby crowds at the box office and the occasional acquisition of a masterpiece are the hallmarks of achievement. On the other hand, the post-imperial confusion of Europe is illustrated by the popular rejection of the EU Constitution with its uncomfortably big tent. For now, parochial or national concerns seem to have won out over international compromise. But in the cultural sphere, at least, MacGregor's administration offers the hope of trading in single-institution or single-nation concerns for supranational ones in service of a worthy goal.

There are bumps ahead on the trail, mostly involving restitution claims. The stance favouring the retention of earlier acquisitions while adopting an ethical approach going forward is under constant pressure, most recently because of the Italian return of the Axum obelisk to Ethiopia. Egypt is now calling for the return of the Rosetta Stone. A reasonable position is that due diligence on the legal title of suspicious recent acquisitions is essential retrospectively as well as prospectively, and that highly selective returns of long-held objects and monuments should be carefully considered, but that reflexive capitulation to nationalistic demands would lead to anarchy. The adjudication of when to accede to claims and when to reject them is the most delicate challenge facing the leaders of encyclopedic museums. And the BM has yet to articulate a concerted approach to restitution claims that rests not merely on British law (which favours retention, exemplified by a recent High Court decision to enjoin the BM from returning four Old Master drawings known to be Nazi loot, see p.53), but on a moral footing no less sure than that applied to future acquisitions. Regardless of the fate of individual objects, only through the efforts of enough institutional leaders can ethically neutral postures become less prevalent than ethically explicit ones. What will next be seen is whether Mr. MacGregor's peers on both sides of the Pond are tugged more towards the heart, even if led there by the head.