In December 2020, the New York Center for Foreign Policy Affairs, a nonprofit think tank, filed a lawsuit in US District Court over a pending US arms deal to sell F-35s and Reaper drones to the United Arab Emirates (UAE). The lawsuit argues the proposed sale should be found invalid because the “administration failed to provide a reasonable explanation” for its approval, placing it “in breach of the Administrative Procedure Act”. When the new Biden administration decided in 2021 to proceed with the sale, the think tank responded by adding new plaintiffs “directly affected by UAE sponsored aggression through the use of US made arms”. Few expect the lawsuit to succeed, but it demonstrates a new approach by US civil society to change US arms-sales practices. NGOs have used similar strategies against weapons suppliers in France, Italy and the United Kingdom. Such lawsuits may be aimed at arms companies or governments (sometimes both) and tend to cite violations of obligations under national law, as well as EU law and the UN Arms Trade Treaty (ATT) where relevant. In 2019, a group of NGOs filed a Communication with the International Criminal Court to investigate the potential complicity of European arms executives and officials with war crimes in the Yemen conflict. Although the ATT contains no enforcement mechanisms, cases like these suggest an important role for civil society, and NGOs especially, in creating accountability to humanitarian arms-export standards in national or international law. Public opinion alone is typically not enough – even in democracies – to prompt governments to practise arms-trade restraint. Except in rare cases, the public does not track the goings-on of the conventional arms trade. As a result, NGOs with expertise and access to information can be important for raising media attention, mobilising public awareness and lobbying policymakers to engage in more ‘responsible’ arms-export decision-making. A case in point are recent US debates over arms sales to Saudi Arabia and the UAE in light of the ongoing Yemen conflict. US domestic export rules direct the executive branch to take conflict “into account” in making arms-export decisions but do not prohibit arms sales to conflict zones. In general, US arms transfers also do not tend to generate public and media attention. But the Yemen conflict and the US role in supplying it have created moments of rare American public outcry against US arms sales. Across party lines, a majority of Americans think “selling weapons to other countries” makes the United States “less safe”, according to a 2019 survey. Many NGOs and think tanks have been pivotal in building on heightened media attention about the war to sway public and congressional opinion in favour of restraining US arms sales in light of their humanitarian consequences. These efforts reveal both the importance of public pressure and its limitations for arms-trade accountability. By late 2015, some senators had begun to question US arms sales to Saudi Arabia. In November, the Senate Foreign Relations Committee made its first-ever formal request for a 30-day notification of sales from an administration. Yet other members saw the precision-guided munitions on order as a way to help Saudi Arabia avoid civilian casualties. A September 2016 joint resolution to block a proposed tank sale to Saudi Arabia failed to pass. Indeed, the need to muster a two-thirds veto-proof majority in both houses has made Congress structurally incapable of formally stopping or modifying US arms sales approved by the executive branch. Rather than congressional action, it was reports of a Saudi air strike on a funeral hall in October 2016, killing more than 100 people, that prompted the Obama administration to put on hold the planned precision-guided munitions sale. The Trump administration decided to proceed with the sale. It was only in June 2019 that Congress succeeded in passing a set of joint resolutions to block a series of arms sales to Saudi Arabia and the UAE. President Trump vetoed the resolutions, and the Senate failed to reach the two-thirds majority to override the vetoes. Congress has never been able to reach the two-thirds voting threshold necessary to override the presidential veto to block or modify a proposed arms sale. The effects of political opposition to proposed Saudi/UAE deals have been indirect at best. The Obama and Biden administrations have rejected some sales in response to pressure from Congress and the media. Setting these aside, though, the US generally continues to supply long-term friends and customers with political and economic objectives in mind.