The British Court of Appeal has ruled that British arms sales to Saudi Arabia are unlawful, on the grounds that British ministers had “made no concluded assessments of whether the Saudi-led coalition had committed violations of international humanitarian law in the past, during the Yemen conflict, and made no attempt to do so.” This ruling offers further proof, if any is needed at this point, that the primary – and indeed, the only – purpose of the Arms Trade Treaty (ATT) is to constrain the Western democracies.

The latest ruling follows from a 2017 High Court decision which found in favor of Britain’s arms sales. I analyzed this ruling for Forbes, pointing out that the case was “rooted in Britain’s adoption of a legally-binding policy that it has committed to follow when granting export licenses for arms and other military goods.” That policy, in turn, reflects the Arms Trade Treaty, though it has earlier precedents.

At the time of the High Court’s ruling, I noted that “On the substance of the case, I agree with the Court. But my own view is that while the Court got it right in its first and third conclusions, its second . . . is less persuasive.” I am therefore not surprised that the Court of Appeal has decided against the government.

The effect of this ruling is hard to predict. Liam Fox, the Secretary of State for International Trade, has promised to appeal, and in any case the Court of Appeal has required only a review of Britain’s arms sales, not their termination. As Fox states, the decision concerns only “the rationality of the process used to reach decisions,” not the rightness or wrongness of the sales themselves.

All this is too serious to laugh at, but, honestly, that is my inclination. The fact is that British policy in the Gulf has been legally hamstrung, at least for now, by precisely the same left-wing forces that Britain spent over a decade egging on during the negotiation and initial implementation of the Arms Trade Treaty. I occasionally heard concerns during this phase from representatives of U.S industry that the treaty was just a clever ruse to allow the Europeans to export arms with a seal of approval from the treaty, while leaving the U.S. – not having ratified the treaty – without such a seal.

Well, if that was the game, it hasn’t worked. Instead of pressuring the U.S., the treaty and the coalition surrounding it has exerted its pressure against the British and French in particular. The French have responded by opening a preliminary investigation into three leaking journalists for a possible “compromise of national defence secrets.” Meanwhile, at last August’s ATT meeting in Tokyo, the British “took to making speeches urging that the ATT not become a ‘court of inquiry’ to be used against its signatories, a phrase that left knowledgeable observers chuckling with glee and contempt.”

Fortunately, in the U.S., President Donald Trump has announced that he will unsign the ATT. That was the right decision, and the latest court case in Britain illustrates why. You would think that this British precedent might make the treaty’s supporters in the State Department nervous.

Apparently, though, they think it can’t happen here. Well, their British colleagues undoubtedly felt the same way. It turns out Britain was wrong: the ATT advocated by Britain has turned out to be a weapon against Britain. That is an excellent reason for us to get out of a treaty that, as the White House rightly put it, provides “a platform for those who would seek to constrain our ability to sell arms to our allies and partners.” That is nothing less than the truth, as the latest British court case proves conclusively.