In this Oct. 14, 2016 photo, fire and smoke rise after a Saudi-led airstrike hit a site believed to be one of the largest weapons depots on the outskirts of Yemen's capital, Sanaa. (Hani Mohammed/AP)

The British government was surprisingly defeated in court on Thursday, as judges ruled that arms exports to Saudi Arabia would have to be reviewed. International Trade Secretary Liam Fox subsequently announced that no new export licenses would be granted until an analysis of the ruling’s implications had been completed.

The Campaign Against Arms Trade had challenged the government over its exports to Saudi Arabia, arguing that the risk the equipment would be used to violate human rights and international law in Yemen weighed too heavily to grant export licenses. British law states that weapons exports should not be approved if there is a risk that the equipment could be used for human rights abuses.

In their ruling, the appeal court judges explicitly criticized that the British government had not assessed that risk “and made no attempt to do so.” They ruled that this process was “unlawful."

For now, their decision will trigger only a review of certain exports and not an immediate halt.

The British government said it would seek to appeal the ruling, but campaigners celebrated Thursday’s developments as major progress.

Being forced to assess the human rights impact of their exports before granting licenses could put the British government in a difficult position: Either it would have to dismiss the alleged human rights violations and risk future lawsuits, or it would have to risk a spat with the British weapons industry that heavily relies on the sales to Saudi Arabia. About 40 percent of all British weapons exports are headed to Saudi Arabia, including fighter jets and precision-guided bombs, which means that thousands of British jobs may depend on those sales.

A worst case scenario for British arms manufacturer BAE Systems and other companies would be a halt of all future exports, even those connected to previously approved sales.

Such a scenario would also prove challenging for Saudi Arabia, because exporters usually sell entire weapons systems to buyers. Those deals typically include years-long maintenance and access to high-tech substitute components. If the export of such components were to be restricted, other nations would not immediately be able to replace Britain.

“This ruling is huge,” Sam Perlo-Freeman, a research coordinator at CAAT, told Al Jazeera.

“It is historic in terms of the government’s approach to export licences being found to be illegal and adds huge momentum to the campaign both in this country and internationally for a halt to arms sales to Saudi Arabia and the Saudi-led coalition,” Perlo-Freeman said.

The British ruling on Thursday came hours before the U.S. Senate passed measures to block President Trump, using his emergency authority, from completing arms sales worth more than $8 billion to Saudi Arabia and the United Arab Emirates. Trump is expected to veto the resolutions.

Opponents of the trade relationship argue that Saudi Arabia and its coalition in Yemen have relied on U.S., British and French weapons to attack targets in Yemen. Their trade ties, critics argue, have made the export nations effectively complicit in what they say constitutes the indiscriminate killing of thousands of civilians — and war crimes. Almost 100,000 people have already died in the conflict, according to a report released this week.

For years, the Saudi-led coalition has sought to dislodge the Shiite-led Houthi rebels, triggering a spiral of violence that destroyed Yemen’s infrastructure, economy and aid delivery network.

Questions over Western nations’ responsibility for the escalation through their exports emerged early on. Germany, which used to be a major arms equipment exporter to Saudi Arabia, gradually reduced its sales to the kingdom over human rights concerns and halted them entirely last year, after the killing of Washington Post contributing columnist Jamal Khashoggi in the Saudi consulate in Istanbul. Parts of the German exports halt have since been relaxed, but the swift decision by Chancellor Angela Merkel last year put an uncomfortable spotlight on the United States, Britain and France, which have all resisted efforts to halt sales entirely.

But human rights groups maintain that the evidence in favor of following Germany’s example is strong. An Amnesty International investigation, for instance, found British-manufactured cluster munition in Yemen.

Under British and European Union law, weapons sales are illegal if it is clear that they could contribute to international humanitarian law violations.

London’s high court initially followed the government’s assessment in 2017 that this was not the case, largely relying on confidential documents. Two years on, the appeals process to that verdict is now threatening to upend decades-long governmental practices.

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