A momentous change has occurred in western Europe over the last 25 years, the transition from emigration to immigration status for most of its societies. Ireland is one of the last countries to experience the transition and is encountering many of the same difficulties adapting to it. It makes sense to compare Ireland with others as we go through the same processes in the age of mass migration and human trafficking so well documented in this week's series of Irish Times articles.

In the post-war years Italy, Spain, Portugal, Greece, Finland, Yugoslavia, Turkey - and Ireland - were the source of labour for other European countries, as well as sending people to the United States and elsewhere in the developed world.

Going back further one can readily see how emigration and colonisation characterised even the most developed states during their periods of imperial and economic hegemony.

Labour shortages in the post-war period changed the pattern for Germany, France, Britain, the Netherlands and Belgium, drawing in millions of people from the European periphery and former colonies. Shortages were reinforced by demographic stagnation, which seemed to accompany economic development. That has gradually affected the European periphery too.

A Swedish study to be discussed at next weekend's European Union summit on economic policy in Stockholm has concluded that fertility in all the 15 EU states and 12 out of the 13 applicant ones is too low to maintain population at current levels, leaving Turkey as the only exception - though the rate of increase is coming down sharply there too.

This coincides with burgeoning labour shortages in the main European economies, another preoccupation at Stockholm. The European Commission has floated plans to co-ordinate immigration policy across the EU, demonstrating that on these trends tens of millions of people will be required in coming decades to fill the demand for labour. That can only be met by bringing people from outside Europe.

Another Commission study found that expectations of mass migration from central and eastern Europe have been much exaggerated. People there would much prefer to stay at home.

That should reassure those who fear for their jobs, especially in border areas. But it will disappoint industrialists and others anxious to find suitable labour, including those in Ireland who have influenced the Tanaiste's plans to attract 200,000 workers over the next decade.

This Janus-faced attitude to immigration may be found across all the EU states. It is expressed in the division between justice ministries which concentrate on security and criminal issues of migration and economic and foreign ministries more concerned with economic growth. The language habitually used to describe the issues often obscures the need for much more "joined-up government" at national and supranational levels if these preoccupations are to be rationally addressed.

Thus defining migration in terms of an emergency or crisis requiring security solutions to restore order and normality assumes it is a temporary phenomenon rather than an enduring feature of an unequal world in an era of globalisation. The phrase "illegal trafficking" can imply returning to a fortress policy rather than to one that is open to the free movement of peoples. As Walter Benjamin put it, "the tradition of the oppressed teaches us that the `state of emergency' in which we live is not the exception but the rule".

International flows of labour have been part and parcel of the capitalist world economy since the seventeenth century. Until the 20th century they were left largely unregulated, which was just as well for the millions of Irish who emigrated. Passports, for example, were more commonly used to control internal migrations within empires than for regulating inter-state travel.

THE dark side of the 20th century gave us the phenomenon of mass refugee displacement after world wars, revolutionary change, imperial collapse and ethnic cleansing.

They have continued after the Cold War, just as they began that century and provided some of its most distinctive characteristics.

The challenge for the new century is to find a way of combining regulation with openness in dealing with migration. Tension between them is exemplified in the confusion between refugee status and economic migration.

That has helped cause a dramatic increase in the black economy to an estimated 16 per cent, from 5 per cent in the 1980s.

There are similar and related tensions concerning citizenship.

Limited rights have been built up for migrant workers as a result of international human rights law and varying national approaches in the EU. The term denizenship describes the accumulation of rights associated with residence, falling short of full national citizenship.

Unfortunately the development of European citizenship law so far excludes third country nationals. The political argument between citizenship based on residence and ethnicity or blood line will continue to inform the debate on migration and migrants' rights.

It draws together many vital political strands. A more inclusive definition of European citizenship will be necessary if migrants are to be accommodated politically and legally. But that development is resisted by states involved in successive renegotiation of the European treaties. The issue will come up again as the Charter of Fundamental Rights in the Treaty of Nice is debated while it is ratified and in the more constitutional debate about the EU political structures set for 2004.

A more inclusive definition of citizenship would take full account of residence and the working lives of migrant workers, who have made a signal contribution to development. It would take more realistic account of the complexities of combining worldwide migration and national particularisms and sovereignty.

Migration has made for a much more multicultural Europe, containing as many foreign-born populations in many states as in the United States. The realisation that they have much to offer in higher- as well as lower-skilled occupations has helped transform attitudes and counter racism and xenophobia. That debate will continue to affect the political fabric of democracy in Europe.