The international arms trade confronts us with several pressing moral questions. Principal among these is the question of whether there should even be an arms trade: should international markets in weapons simply be abolished? As I have argued elsewhere, the strongest case for the maintenance of an international arms trade appeals to the universal human interest in security. This interest grounds a right to security, and this right places on governments a duty to protect the physical safety of their citizens. Weapons enable governments to discharge this duty, and an arms trade can be an efficient means of ensuring that governments can acquire weapons of adequate quality and in sufficient quantities.

If we think an international arms trade should be permitted to exist in some form – or if we recognize that the arms trade will continue to exist, irrespective of whether it should – a second moral question arises. This question concerns the scope of the arms trade, and asks who should be permitted to buy weapons. This is a crucially important issue. The failure of politicians to impose appropriate limits on the scope of arms markets accounts for the most serious moral deficiencies of the international arms trade. States regularly permit the sale of weapons to oppressive regimes that should be excluded from the market, and this behaviour looks set to continue even now that the Arms Trade Treaty has entered into force. Some of the world’s largest arms exporters – including the US – have not ratified the Treaty, and even some of those that have seem intent on interpreting its constraints rather loosely. The UK, for example, continues to supply weapons to Saudi Arabia, a country ruled by a notoriously oppressive regime.

A moment ago I noted that the right to security places on governments a duty to protect their citizens. But it also places on governments a duty to refrain from inflicting upon any person (citizen or otherwise) undue physical harms. When governments inflict such harms they violate people’s right to security. Clearly, regimes that oppress their own citizens are guilty of violating security-rights. But those rights are also violated by states that arm such regimes. When a state arms an oppressive regime it facilitates, and thus becomes complicit in, that regime’s abuses. As I have argued in the past, arms transfers to an oppressive regime contribute to the infliction of undue harms in a number of ways. They provide the regime’s security forces tools with which to coerce, maim, and kill; they bolster the regime’s ability to quash uprisings; they enhance the power of the regime relative to third parties with the capacity to intervene; and they demonstrate to the regime that opportunities for valuable forms of international cooperation (such as trade) will be available regardless of whether or not it respects basic rights.

When governments approve the sale of weapons to countries like Saudi Arabia, they might reason as follows: oppressive regimes will inevitably get weapons from somewhere, so they may as well get them from us. This argument trades on the thought that it makes no difference whether or not we permit arms sales to oppressive regimes, for those regimes will get what they want irrespective of what we do. But, as I have argued before, this reasoning suffers from a number of flaws. First, when governments allow domestic companies to offer weapons to a particular regime, those companies can increase the competitiveness of the market, driving down prices and thereby enabling the regime in question to buy larger quantities of weapons. Second, domestic companies may be offering certain kinds of weapons, or weapons of an especially high quality, which rival suppliers lack, and which would otherwise be unavailable to the buyer. Third, governments that refrain from selling weapons to oppressive regimes can try to persuade their foreign counterparts to do likewise, and if persuasion is unsuccessful they can impose sanctions. But clearly these options are not available to a government which is itself in the business of arming oppressive regimes. In short, how governments behave does make a difference, and politicians in Britain, the US, and elsewhere should recognize this.

If the international arms trade can be justified it is by appeal to the right to security. But that right also imposes strict limits on the scope of the arms trade. Governments must not approve arms sales to oppressive regimes. When they do, they become complicit in those regimes’ crimes.