Though it acts as a court, it has no official status. The governments asked to participate have either snubbed or (in the case of China) condemned it. Some witnesses, under threat of sanctions from Beijing, started dropping out before its proceedings had even begun. And yet, the Uyghur Tribunal, whose final hearings took place in London in September, is an institution nobody can afford to ignore. It offers the best hope yet of answering a pressing question: is China committing genocide against the Uyghurs, the 12 million Turkic Muslims in the northwestern region of Xinjiang?

A series of testimonies from the region, collected by organizations such as Human Rights Watch and publications including the Washington Post, the Independent, and the New Yorker, indicate that since late 2016, Xinjiang has been transformed into a nightmarish police state, where Uyghurs are spuriously arrested, detained, subject to forced labor, raped, tortured, separated from their spouses and children, and forced to confess to non-existent crimes. The scale is unclear, but satellite imagery suggests that at least 1 million, and perhaps three times that, have suffered imprisonment at some point. A leaked memo showed that in a single week in 2019, the authorities in southern Xinjiang seized over 16,000 citizens, with 5,500 more recorded as “temporarily unable to be detained.”

The repression is brutal in its ambitions: Chen Quanguo, Xinjiang’s governor, has proclaimed a “smashing, obliterating offensive,” pledging to “bury the corpses of terrorists and terror gangs in the vast sea of the People’s War”—an especially disturbing turn of phrase given that people are suspected of terrorism if they socialize too little or have the wrong kind of beard. It is a frighteningly high-tech kind of persecution. Surveillance cameras are programmed to recognize Uyghur faces, all cars have state-issued GPS trackers, phone data is exhaustively harvested, and QR codes are affixed to houses to provide instant information to the police. It is dehumanizing in the most fundamental ways. One Uyghur doctor, now in Istanbul, told ITV that as part of a government-run “population control plan,” she had taken part in more than 500 operations on Uyghur women including forced contraception, abortion, and sterilization. The question—one question, anyway—is whether all this meets the legal definition of genocide.

In the “Yes” camp are the U.S. State Department, during both the Trump and Biden administrations; the British, Canadian, Dutch, and Lithuanian parliaments, which have voted to declare a genocide; and—to some extent—four barristers from Essex Court Chambers in London, whose 105-page legal opinion concluded that there was a “very credible” case for using the term. The barristers pointed in particular to evidence of widespread sterilization, as well as the separation of children from parents. Was there, as international law requires, a “genocidal intent”? That is harder to prove, they reckoned, but leaked documents from central and regional governments, laying the groundwork for the repression, suggest that President Xi Jinping and Xinjiang governor Chen Quanguo could indeed be convicted of this “crime of crimes.”

The “No” camp includes the scholars William Schabas and Jeffrey Sachs, who have argued in Project Syndicate that, although there is evidence of “a gross violation of human rights,” the essential element of genocide—the intent to destroy a group—is far from proven. Others, including Amnesty International and Human Rights Watch, are on the fence. Boris Johnson has said that the definition is a matter for the courts.

Indeed it is, but China is not a member of the International Criminal Court; and the U.N. cannot, in practice, summon the International Court of Justice to investigate, given China’s veto power on the Security Council. A national court, or a court appointed by several countries, could try the matter, but governments have avoided setting one up. That leaves only one option.

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After two four-day sessions in June and September, the tribunal is now working on its verdict, expected in December. It will have to answer two questions: first, what conclusions can be drawn from the evidence, the satellite imagery, leaked government documents, and copious first-hand testimonies? Second, a major theoretical issue: what is the threshold for genocide?

The word is one of the most potent neologisms of the 20th century, coined by the Jewish-Polish lawyer Raphael Lemkin around 1944 and codified by the U.N.’s Genocide Convention in 1948. When I spoke to Sir Geoffrey Nice, he acknowledged the difficulty of pinning down a definition. “The public citizen has been given this word,” he says. “Can you imagine being as powerful after your death as Lemkin, in giving every educated person on the planet this new word? They didn’t have it before; now they’ve got it. What a phenomenal success. But, they don’t really know how”—he pauses—“they know how to use it, but they don’t really use it accurately, according to the law.”

Contrary to one fairly common misperception, genocide is not a matter of numbers. Although the Khmer Rouge murdered over a million Cambodians, the courts didn’t count this as genocide, because there was no intent to destroy a people. However, Khmer Rouge leaders were convicted of genocide for the numerically slighter killing of ethnic minorities, the Cham and Vietnamese, because there appeared an intent to destroy an identifiable group.

It also doesn’t mean total destruction. The Bosnian commander Radislav Krstic, convicted of genocide for his role in the 1992 Srebrenica massacre, appealed on the grounds that Srebrenica’s Muslims were only a fraction of the Bosnian Muslim population. The International Criminal Tribunal rejected his appeal, saying that his intent was effectively genocidal even if he only got the chance to carry it out in one place. As the tribunal noted, the Nazis didn’t make a plan to destroy the Jewish population outside Europe, but the Holocaust is still the supreme example of genocide.

Raphael Lemkin defined the crime as “a co-ordinated plan of different actions aiming at the destruction of essential foundations of the life of national groups.” Since then, scholars and courts have mulled over what constitutes the “life” of a “group” and what is “essential” to it. Lemkin also wrote of “cultural genocide,” the devastation a group’s linguistic and historical identity. Advocates of a genocide conviction point out that the Uyghur language has been suppressed and, in at least one prefecture of Xinjiang, completely banned from the classroom. The Uyghurs’ religion has received similar treatment: one official in Kashgar, according to the New Yorker, boasted that “we destroyed nearly seventy percent of the mosques in the city.”

The key legal text, the Genocide Convention, laid down five acts by which a perpetrator could intend “to destroy, in whole or in part, a national, ethnical, racial or religious group, as such.” Killing is one of those acts; enforced birth control, and the transfer of children, are also on the list. The other two are more nebulous: “causing serious bodily or mental harm” and “deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part.”

Like Lemkin’s original definition, these phrases are open to interpretation. Legal precedent only gets you so far. As Sir Geoffrey observes to me, unlike in previous cases, “there is no suggestion of mass killing. It’s all the other limbs, which have never been the subject of a formal court determination, which we’re having to deal with.”

If China is declared guilty of genocide, that would strengthen the case for international sanctions; for multinationals to cut or reduce their ties with the country; and for organizations and individuals to find their own ways of expressing solidarity with the Uyghurs. They could, of course, do that anyway, and it is tempting to dismiss the genocide debate as needlessly complex, a terminological question that obscures a plain moral imperative.

Sir Geoffrey Nice, however, believes the legal nuances are no reason to abandon the term. “It suited the politicians and the lawyers at the time to hand out this definition. They shouldn’t then be allowed to take it away by saying, ‘Oh, no, it’s too difficult to use.’ You can’t give and take away at the same time.”

The Genocide Convention was the first ever treaty passed by the U.N. General Assembly: it represents, in some ways, the beginnings of the post-war international order. Over the next few years we may discover how much of that order remains.

Dan Hitchens is former editor of the Catholic Herald.