There are several now classic defenses of state’s rights to control borders.

David Miller (Miller 2005, 2007), Michael Walzer (Walzer 1983) and Christopher Wellman (Wellman and Cole 2011) have been particularly important.
Joseph Carens is the most influential proponent of the alternative “Open Borders” position (Carens 1987, 2013, but see also Cole 2000 and Wellman and Cole 2011). While many theorists discuss the responsibilities to refugees
and guest workers, Walzer’s treatment is particularly influential, especially in arguing for his view that guest worker programs are only justified when they offer such “guests” a proper pathway to full and equal citizenship
(Walzer 1983). Wellman offers comprehensive discussion of defensible admission criteria (Wellman and Cole 2011). Whether brain drain issues should be salient for migration decisions has been the subject of recent discussion
(Carens 2013, Oberman 2012, Brock and Blake 2015). For detailed coverage of issues concerning whether borders should be more or less open, what our obligations are to refugees or guest workers, and issues concerning the
ethics of recruiting immigrants away from poor, developing countries, see the entry on immigration.

7. Global Environmental Issues

Patterns of human behavior that destroy habitats, accelerate species extinction, exacerbate toxic levels of pollution, contribute to ozone layer destruction, or increase population levels are all issues of global environmental
concern. However, although there are many global environmental topics that are rightly concerns of global justice, there is one that dominates discussion and that concerns our responsibilities with respect to climate change.
Here we focus exclusively on this issue.

Among the scientific community it is no longer controversial that anthropogenic climate change is real and a significant threat to the well-being of both current and future generations. But it is also widely acknowledged that
human development is an important way to address high levels of global poverty, that such development is energy intensive, and the cheapest sources of energy available are not likely to be clean energy types. These
considerations significantly affect efforts to deal with problems presented by climate change. There is much discussion about the principles that should inform a fair treaty aimed at dealing with addressing climate change that
also gives appropriate weight to concerns for human development. Some of the main contenders include principles that recognize causal responsibility for high emission levels, principles that are sensitive to ability to pay, and
ones according to which those who have benefited from emissions should now be expected to absorb more costs.

We have not all contributed equally to the problems created by emissions; industrialized nations have contributed historically at much higher levels than those that are still developing. And so we should endorse the guidelines
that those who have polluted more should pay more to help redress current problems (The Polluter Pays Principle). However critics argue that this principle unfairly holds some responsible when they did not know they were
causing harm, since it was not widely known that greenhouse gases could result in climate change prior to 1990. So on this view, responsibility for emissions prior to 1990 should not conform with the Polluter Pays Principle,
even if it is used to allocate costs after 1990. A second principle that is often discussed is The Beneficiary Pays Principle. Those who live in industrialized countries have typically benefited greatly from high levels of emissions
so it is not unfair if they are expected to pay a higher proportion of costs. Critics object that a history of benefiting is an insufficiently strong consideration for assigning responsibilities now: in many cases whether or not people
benefit is largely outside of their control. According to a third popular principle, The Ability to Pay Principle, the capacity of agents to pay for costs associated with mitigating climate change should be relevant.

Comprehensive treatment of climate justice requires addressing the issue of responsibilities to future generations. For important treatment of our responsibilities to other generations see the entry on intergenerational justice.

8. Global Health Issues

One striking feature of the state of global health is that there are large inequalities in health outcomes and opportunities for health. Consider that life expectancy can vary a great deal. A person born in Sierra Leone can expect to
live about 40 years whereas one born in Japan can expect to live for 80 years. Malaria has been almost entirely eradicated in high-income countries, but it still kills about a million people in developing countries (United
Nations 2009). A woman in the Niger has a 1 in 7 chance of dying in childbirth, whereas this is 1 in 11 000 for women in Canada (Benatar and Brock 2011). The global burden of disease is by no means evenly spread nor does
workforce capability correspond with areas of highest need. In fact many of the countries that suffer from the greatest burdens of disease have the fewest skilled healthcare workers. In addition, pharmaceutical companies do not
spend their research and development budgets in ways that match where the needs are greatest. Rather, seeking the most profitable ventures, they are much more likely to spend resources developing drugs for lucrative markets
where the payoffs are greatest, even when the marginal benefits to consumers are small. One example is the research and development resources pharmaceutical companies frequently spend on developing drugs that are similar
to others already available, rather than developing treatments for diseases for which there are no cures. It is estimated that drug companies spend approximately 90% of their research and development resources in seeking
treatment for about 10% of diseases (Drugs for Neglected Diseases Working Group 2001).

The poor in developing countries are also often more vulnerable to disease and less able to resist disease because of poor living conditions related to poverty. Lack of clean water, clean energy sources, inadequate nutrition, and
other social determinants of health play a key role in explaining this increased vulnerability. Living in overcrowded houses can facilitate the spread of infectious diseases, such as tuberculosis. So, a number of issues that sustain
poverty or exacerbate people’s vulnerability to disease as a result of poverty should be of concern (Benatar and Brock 2011). As Norman Daniels argues, health inequalities among different social groups can be considered
unjust when they result from unjust distribution in factors that are socially controllable that affect population health (Daniels 2011, 101). On this view many of the health inequalities that exist are ones that ought to be of
concern as they meet this criterion. How should responsibilities for improving this situation be allocated? In many ways, but here I pick out just a few that have received considerable attention in the philosophical literature.

The current system of intellectual property rights is one troubling area. The World Trade Organization grants product patents for a twenty year period which effectively renders many new medicines unaffordable for the vast
majority of the world’s population and those in greatest need. There are a number of innovative proposals aimed at addressing these issues. One prominent example is the Health Impact Fund proposal developed by Thomas
Pogge, which offers alternative ways to reward pharmaceutical companies, notably by how much impact they have on actually curing diseases (Pogge 2008). The greater their impact, the larger the share of the rewards they
would receive from the Health Impact Fund. Nicole Hassoun proposes a certification program for rating pharmaceutical companies’ contributions to the global poor, “Fair Trade Bio” (Hassoun 2012). Companies would
compete for the gold star rankings which could significantly affect consumption choices and thereby expected profits. In both cases the aim is to create important incentives for key players to care about how their products