The United States Embassy has rejected allegations that language within a draft bill introduced by a US Senate committee last year sought to sway the investigation into alleged Khmer Rouge naval commander Meas Muth.

The draft language – which was later removed – was criticised in a decision by the court last week to proceed, at least for now, with the government-opposed Case 003 against Muth.

But in spite of the US denial, some, including the lawyers for the defence, contend that the “soft power” impact of the US should not be underestimated in a court that has been plagued by claims – usually directed at the Cambodian government – of outside interference.

The draft bill, sponsored by Republican Senator Lindsey Graham of South Carolina in July 2016, highlighted American interest in Muth by proposing to tie US contributions to his case, as he was “implicated in the 1975 Mayaguez incident”, which cost American lives.

The bill also endorsed a “plan to cease contributions” to the tribunal if Case 003 was closed.

The draft may have been a counterpoint to the Cambodian government’s open disdain for the case against Muth. Prime Minister Hun Sen, a former Khmer Rouge soldier himself, is overtly opposed to Cases 003 and 004 going ahead, and has threatened civil war would ensue if they did.

The final bill allocating funding to the court was passed in early May – the same week a “permanent stay” was proposed in Muth’s case – with the reference to Muth wiped clean from the final version.

Nonetheless, in their Friday decision to hold off on issuing a permanent stay, the judges for the first time expressed their concerns that the draft bill had put them in a double bind – indict Muth and face criticism for having “caved”, or dismiss the case and forego funding.

However, US Embassy spokesman Arend Zwartjes rejected that interpretation.

“The allegation that U.S. assistance is contingent upon issuance of any particular indictment is simply incorrect. As the order itself acknowledges, no such provision exists in U.S. law,” Zwartjes said in an email.

The US has so far contributed more than $32 million to the tribunal over the past decade, including a recent pledge of $1.5 million.

“If a single principle has guided us over that time, it is the belief that it is the responsibility of the court, not governments, to determine the fate of the Khmer Rouge defendants,” he said.

However, the idea that funds could be tethered to a certain outcome appeared firm in the judges’ minds. They wrote in the order “the only reasonable interpretation” to the draft was that the US could stop their funding altogether if they didn’t agree with the findings on Muth.

“It does not require much imagination to realise the position that the text of the original bill alone put us in,” they said.

“The version of the enacted legislation does not contain the same crude conditions as the bill but does at the end of the day do little to assuage our concerns.”

Muth’s defence lawyer, Michael Karnavas, noted that even a draft bill “does carry weight, and has the potential of interfering with judicial independence”.

“It carries the sting of soft – yet not-so-subtle – intimidation. It is hypocritical to think otherwise,” he said.

“The mere inference that funding is dependent on a particular result and not on the proper administration of justice . . . casts a dark shadow, which can, and often does, tarnish the integrity of the proceedings and the court in general.”

Expecting a guilty verdict in exchange for US investment in the tribunal does not “square with the rule of law”, he said, “but it does square with the proverbial golden rule: he who has the gold makes the rules”.

Tribunal observer Heather Ryan, of the Open Justice Society Initiative, said the language in the draft bill was “an unfortunate and inappropriate intervention by a funder of an independent court” that was fortunately recognised before the final bill.

“As with inappropriate statements from other sources, including the government of Cambodia, regarding the outcome of specific cases, hopefully the investigating judges can ignore the implications,” she said.