An investigating judge has rejected Kem Sokha’s request that he interview a representative from the US government in connection with the former opposition leader’s “treason” case, despite the fact that Sokha stands accused of plotting a US-backed overthrow of the Cambodian government.

According to Sokha’s lawyer Peng Heng, the request, filed in January, was rejected on Wednesday.

The judge reportedly claimed that a 2013 video in which Sokha tells a crowd of supporters that he received political advice from America was sufficient evidence on the matter. Sokha was arrested in a midnight raid in September, with the 2013 video serving as the only evidence of his purported treason.

“The Phnom Penh Municipal Court prosecutor charged Kem Sokha of colluding with foreigners, it is normal for the investigation judge to ask about the facts involving the US as well,” the original request reads.

Heng said the rejection was “not reasonable” and felt that the court was not interested in gathering evidence from Sokha’s side.

“When the investigation is not wide, justice is limited,” he said.The legal team will confer with Sokha on whether or not to appeal the decision.

Sokha’s party – the Cambodia National Rescue Party, the country’s only viable opposition – was summarily dissolved at the government’s behest just months ahead of national elections for its alleged role in foreign-backed “colour revolution”. Most observers condemned the charges as a pretence for the ruling Cambodian People’s Party to rid the electoral field of its only legitimate challenger.

The US Embassy declined to comment on Sokha’s case yesterday, but Ambassador William Heidt has previously called the accusation against the US “absurd” and made without “a shred of serious or credible evidence”.

Former CNRP Deputy President Mu Sochua said in a message that the rejection of the legal team’s request was more evidence that Cambodia’s “courts are not independent”.

There is “no sound evidence whatsoever to move the case forward if [Sokha’s] request is approved”, said Sochua, who fled the country following Sokha’s arrest after being warned her own incarceration was imminent.

Sochua went on to say that the courts “would not dare face a US citizen” because they operate by “their own rules not international standards of fair trial”.

Political analyst Meas Nee, meanwhile, said the entire case was “politically motivated” and must be analysed in that context.

“I don’t think the court will want to expand to more investigation,” he said.

Nee said another reason the court may have balked at the recommendation, was that it could embarrass Cambodia on an international stage to explicitly involve the American government in the trial process.

“If they investigate and found nothing it would be shameful to the Cambodian government, because the allegation has no proof,” he said.

Kingsley Abbot, International Legal Adviser at the International Commission of Jurists, said in an email that Sokha’s right to call witnesses is a “fundamental element of the fair trial right to a defence”.

“This principle guarantees that the accused is not at a disadvantage vis a vis the prosecution and is able to bring before the court any witnesses he considers may be able to provide exculpatory testimony,” Abbot continued.

But concerns about the trial aren’t limited to Sokha’s ability to call witnesses, he added.

“There is a wider concern whether Kem Sokha can receive a fair trial in any event as these proceedings have all the hallmarks of being politically motivated,” he said.

A court spokesman could not be reached yesterday.