[This essay was updated on Nov. 23, 2011]

The United Nations sent its top legal official to Cambodia this week in a belated effort to deal directly with the threatened implosion of a war crimes tribunal charged with bringing to trial leaders of the apocalyptic Communist regime that presided over the deaths of at least 1.5 million people in the 1970s.

Who the leaders are – or were, since many of them, including the notorious Pol Pot, are dead – is the issue at the heart of the current crisis. It is the latest of several problems that have bogged down the court. The tribunal was created in 2003, delayed by decades of political wrangling inside the country and between Cambodia and the UN, with numerous other nations weighing in from the sidelines. It was designed (over objections from the UN) as a joint UN-Cambodian war crimes tribunal, the only one of its kind.

Patricia O’Brien, the head of the UN’s office of legal affairs, will be meeting Cambodian officials most responsible for dealing with the tribunal, which has labored under constant interference from the government of Prime Minister Hun Sen.

In a statement issued this week, O’Brien strongly urged the Cambodian government “to refrain from interfering in any way whatsoever with the judicial process.”

It may be time for the UN to ask whether this court should be moved out of the country if it is to function independently. (The Rwanda tribunal set up after the 1994 genocide was based in Tanzania, though under different circumstances.) A withdrawal by the UN from Cambodia, however, would leave millions of Cambodians separated from a court they were just beginning to view as a source of healing and a rectification of history.

In recent months, the tribunal has lost several staff members and an invaluable adviser, Stephen Heder of the School of Oriental and African Studies at the University of London, who is widely regarded as one of the world’s top experts on the Khmer Rouge. Those departures have now been followed by the resignation of a tribunal judge, Siegfried Blunk of Germany. All cited government interference with the course of justice at the tribunal, formally named the Extraordinary Chambers in the Courts of Cambodia (ECCC), a clue as to how the government perceived the limits of its independence from the start.

Youk Chhang, a United States-trained investigator who heads the nongovernmental Documentation Center of Cambodia in Phnom Penh, which has accumulated a trove of evidence and worked for years to bring village people into the process of seeing justice done, said last week that it was time to look into the office of the investigating judges, to which Blunk belonged. The office also includes his Cambodian counterpart, who has been blatantly doing the government’s bidding. Blunk had earlier been criticized for not standing up forcefully to the challenge sooner.

“If no investigation takes place,” Youk Chhang wrote in a statement, “every entity connected with the ECCC, including the UN itself, will be complicit in compromising the last opportunity to provide some measure of justice for victims of the Khmer Rouge, whose suffering has already been either ignored or politically manipulated for over 30 years.”

From the start, the tribunal has had problems with the government of Hun Sen, a former Khmer Rouge area commander himself. Over the years it became increasingly clear that he intended to limit the court’s cases to about half a dozen well-known figures from the Pol Pot regime, which ruled from 1975 until early 1979. To go much deeper into the leadership might expose people in the Hun Sen administration or its armed forces.

When the court’s prosecutors began to move beyond its first two cases, the government stepped up its threats to close down the tribunal, which is housed in a Cambodian military base. The first of those trials resulted in the jailing of Kaing Guek Eav, the commandant of the Tuol Sleng detention and torture center in Phnom Penh. It sent thousands into the so-called killing fields in the countryside beyond the city limits.

The second case, about to begin hearings on Nov. 21 after years of procedural delays and other legal diversions, includes the four surviving top Khmer Rouge governing officials: Nuon Chea, Khieu Samphan, Ieng Sary and Ieng Thirith. These four cases are combined into one trial. All of the defendants are in their 70s or 80s and not in robust health, causing concern that one or more will not live through the process or will be declared too ill or senile to stand trial if the court does not act more quickly.

Prosecutors want to open two more cases involving a total of five more Khmer Rouge officials, and this move, vociferously attacked by the Hun Sen government, raised the threat level against the proceedings to a new high.

Last week, the US donated $1.65 million to the work of the tribunal, the first installment on a $5 million pledge for this fiscal year. (The court’s budget requirement for 2011 is $40 million.) International donors and the UN support part of the court’s budget; the Cambodia government is expected to raise the remainder. But at this point, money – always in short supply at the tribunal – is not going to end the crisis or correct its fundamental flaws.

[Nov. 23 update: The tribunal began Nov. 21, on schedule, with three of the four Khmer Rouge defendants: Khieu Samphan, Ieng Sary and Nuon Chea; Ieng Thirith, the only woman, was deemed unfit for trial earlier.]