Immigration is one of the most controversial topics in politics today. In the United Kingdom, anxiety about immigration helped propel the vote to leave the European Union in June 2016. In the United States, concerns about immigration from Mexico and Central America featured strongly in Donald Trump’s successful bid for the Presidency. In 2015, forced migration, in the form of hundreds of thousands of people seeking safety from conflicts in Syria and other parts of the Middle East, became central to the European political agenda, with some political leaders calling for a compassionate response to the crisis while others claimed that the flow of ‘genuine’ refugees was mixed with ‘economic migrants’ searching for a better life. Some of these movements were new, but many continued patterns dating back decades or longer. Though readers are probably most keenly aware of the migration events I have mentioned, they are only the most newsworthy parts of the picture. Other countries and regions, such as Russia and South Africa, experience strong inward migration and sometimes social tensions as a result. Many movements of people, such as of nurses and domestic workers from the Philippines to wealthy countries, or of construction workers from Nepal to the Gulf States, get much less publicity.

When politicians discuss immigration, they usually stress the costs and benefits to ‘us’, the settled electorates of the nations in which they are running for office. Politicians from the populist right play to fears about change, about threats to national cultures, about incomers with different religious beliefs, about crime, or about competition for jobs and supposed downward pressures on wages. In countries where economic growth has slowed, where there are many people who have not benefitted from globalization and where living standards have suffered from tight fiscal policies, foreigners, particularly visible ones, are an easy and obvious target for resentment. By contrast, more market-oriented politicians argue for the benefits of immigration: ‘our’ economy needs skilled migrants. ‘We’ need our companies, schools, universities and hospitals to hire the best people for the job, irrespective of their passport. Skilled immigrants can help plug vital skills gaps in sectors like health, social care and construction.

Despite deep differences on both facts and principles, politicians and commentators from the populist right, the ‘neoliberal’ centre and the traditional left share the assumption that immigration policy should be determined by what ‘we’ need. This book is not about whether immigration is beneficial or harmful to ‘us’; it is about something more fundamental. It is about whether states have the right to exclude immigrants and whether people have the right to migrate and make new lives in countries other than those of their birth or nationality. Politicians, commentators and members of the general public who frame the immigration debate in terms of costs and benefits to ‘us’ assume that the state (and democratic electorates) have the right to set immigration policy pretty much as they choose. Indeed, states do have the legal right to do just that. But this book argues that the legal rights states have need moral justification and cannot be taken for granted.

Most of us appreciate the difference between what we personally like and what we have a right to do. I might prefer it if the people coming to live in my part of town shared my economic background or cultural or religious view. It might be better for me if more people like me moved in. It would boost house prices or lead to more shops or restaurants in the local area catering to my tastes. But I have no right (legal or moral) to exclude people different from me from my area and it would be wrong to use personal or political pressure to do so. The right to regulate migration is not so different from the right to decide who can settle in your locality: whatever right there might be to do such things needs justification.

Normative theorizing about migration is likely to encounter resistance from a number of sources. For politicians, policy-makers and many members of the general public, questioning the assumption of state discretionary control can seem absurd and outlandish, particularly where their horizon is fixed by the policy agenda, or by what the electorate might tolerate in the near future. Engaging with politicians and policy-makers can also be dangerous and distorting for the normative theorist, because the pressure to be ‘relevant’ to policy concerns often means that conversations proceed from a tacit assumption that policy-makers’ beliefs about the state’s right to control are justified. Discussion often shifts to helping policy-makers achieve their aims and away from any questioning of the basic legitimacy of those goals.

Activists and social scientists working on migration often have the opposite assumption, namely that all restrictions are bad, and that the state and its officials should be resisted at every turn. Sometimes such a view is based in explicitly anarchist convictions, but often it stems from a close and bitter experience of how states function, and how they damage the lives of vulnerable people. A primitive sense of justice and injustice can be a pretty good guide in the world of immigration policy and enforcement. Such people are wary of arguments that could ever justify state controls, because they think of such justifications as providing ideological cover for what actual states do when the moral imperative is rather solidarity with the oppressed and disadvantaged. I hope this book can persuade both camps that normative theory has something to offer.

The argument has three parts. The first is mainly descriptive: I discuss some aspects of the current migration, border and citizenship regime, how it came into being and its main characteristics. This is necessary because discussion too often takes place against a background of problematic beliefs about migration, the state and the citizen. Nation states, the entities who are trying to ‘control’ their borders, are institutions of fairly recent invention and are neither the natural nor the normal things that they are often thought to be. Many of the particular nation states that exist have boundaries artificially superimposed on much older patterns of ethnic, economic, social and family interaction. The persons who live on the territory over which these states exercise jurisdiction are not all citizens in good standing whose status as ‘British’, ‘French’ or ‘Indian’ is an uncontroversial matter of fact. Rather there have always been large numbers of people who ‘don’t fit’, legally, socially or both. And the current regime of border controls and its documentary accompaniment of identity cards, passports and visas is of very recent invention.

The second chapter is the most theoretical. It asks how we should think about the right to regulate migration and what could justify it. It draws on an insight from the eighteenth-century German philosopher Immanuel Kant, who argued that when we claim a right to a thing or piece of land, we thereby also claim to impose a duty on others not to use it without our permission. Why should they respect our claim? Why is it morally acceptable to use force or threats to enforce it against them? Kant’s answer is that it is wrong to use force unilaterally against others and that rights and duties have to be justifiable from a perspective that both the right-holder and the duty-bearer can share.

In this spirit I ask whether the existing norms around migration that give states an (almost) unlimited discretionary right to exclude are justifiable to everyone: citizens of wealthy countries and poor ones; sedentary citizens and would-be immigrants. I ask which norms might be and argue that rules that could be justified to everyone would permit much more freedom of movement than we have now but that ultimately we need global institutions to adjudicate the various claims and values from a perspective that is fair to everyone.

In the third chapter, I shift focus from the global and universal to the standpoint of particular states and individuals in a world like our own. There is often a difference between first-best solutions that assume that everyone is complying with fair principles and the second-best policies that we should follow when they do not. I ask about what individuals and states should do in an imperfect world where some states are determined to pursue unjust policies no matter what. I argue that individual states should do two things: first, they should make good faith efforts to work with other states to bring a more just global regime into being; second, in their current policies they should anticipate at least the minimal standards of such a regime. They must respect and protect the human rights of immigrants and they should bear perhaps more than their fair share of migration costs, even if they are not obliged fully to compensate for the injustice of other states. Where states act reasonably justly in this way, then citizens and would-be immigrants also acquire some duties towards them to comply with their rules; where states do not act justly then immigrants do not have to obey their immigration rules or give truthful answers to their officials, and citizens must work to change unjust policies and mitigate their effects.