Visitors to Choeung Ek in May burn incense and offer prayers at a memorial housing skulls of unidentified victims of the Khmer Rouge. Photograph: Pha Lina/Phnom Penh Post

When Cambodia almost certainly passes draft legislation today outlawing the denial of Khmer Rouge crimes, it will join the ranks of more than a dozen countries around the world to boast such laws.

But while those countries have provisos within their constitutions making denial laws legal, Cambodia has none, and the apparent unconstitutionality of the law – coupled with the timing – has raised concerns that it will be little more than a dangerous legal precedent and a cudgel with which to silence dissent.

“According to the constitution, every law has to be in line with the constitution,” noted Panhavuth Long, program officer at the Cambodian Justice Initiative. “That kind of proposed law violates the principle of freedom of expression.”

Article 41 of the constitution enshrines the right to freedom of expression as long as it is not used “to infringe upon the rights of others, to affect the good traditions of the society, to violate public law and order and national security.”

Interpreting that exception in such a broad light is unprecedented, say lawyers and rights monitors.

“It is an overly broad interpretation. The international norm is that the exception is the exception and not the rule. We have to go with the strictest interpretation of freedom of expression,” said Cambodian Center for Human Rights president Ou Virak.

On May 20, the Council of Ministers posted a recording on its website in which opposition party leader Kem Sokha can be heard saying that the infamous torture centre S-21 “was staged”.

A day after news of the recording came out, Sokha said the words had been taken out of context, that he meant only to imply the Khmer Rouge made a theatre of Tuol Sleng by forcing confessions, and stressed he had no doubt “about the torture and cruelty that the Khmer Rouge inflicted on Khmer people”.

But amid outcry over the incident, Prime Minister Hun Sen asked parliament to develop a denial law outlawing such statements.

“In Europe, whoever dares to say that Hitler did not kill those people must be guilty,” the premier said in a speech last week, before asking that similar legislation be drafted here.

Holocaust denial laws are widespread in Western Europe, but have also been ruled unconstitutional when raised before courts in a number of countries including Spain, Denmark, Sweden, the United Kingdom and Canada.

In those countries that do have such laws, “denial is something they have struggled with a lot,” pointed out Deborah Lipstadt, a noted US historian and Holocaust expert who has written multiple books on Holocaust denial.

“They have very serious problems there of people saying the Holocaust didn’t happen,” she continued, noting that many European countries have also struggled to tamp down neo-Nazism, whose denial often veers into hate speech, calls for violence and brutal attacks.

In Cambodia, where virtually no one was untouched, either directly or indirectly, by the devastation of the Khmer Rouge, denial is all but nonexistent. The single recent instance in which it has come up publicly – Sokha’s alleged comments regarding S-21 – was rapidly undermined by his vociferous disavowal of such beliefs.

“If [Sokha] keeps jumping back and forth saying today ‘I don’t’ and tomorrow ‘I do deny,’ that’s one thing. But if he insists he was taken out of context,” it would be wrong to count that as denial, Lipstadt said.

“The fight against genocide denial should be a fight against genocide denial. It shouldn’t be a politicised effort to silence opposition. If this is indeed what is being done, it would be exceptionally disturbing.”

If denial doesn’t exist, if the one widely known instance of denial has been, well, denied, what purpose could such a law serve?

“Let’s be honest, this law is certainly political,” said CCHR’s Virak. “It has the motive – it was [drafted] after the audio clip of Kem Sokha and speeches [of Hun Sen]. The motive is pretty clear.”

National Assembly spokesman and CPP lawmaker Chheang Vun dismissed criticisms and insisted the law was “reasoned” against the constitution and wholly valid.

But some fear the law’s true use will hew more closely to that of Rwanda’s genocide denial legislation – which has been condemned by rights groups for stifling political dissent.

In a 2010 Amnesty International report on the laws against genocide ideology and sectarianism, the group warned that the “broad and ill-defined laws have created a vague legal framework which is misused to criminalise criticism of the government and legitimate dissent.”

As with the Rwandan laws, Cambodia’s draft – as it stands – “poses a risk to freedom of expression,” Amnesty International Cambodia researcher Rupert Abbott said.

“Seeing as the freedom of expression situation has worsened in recent years, this could have a general chilling effect on people willing to debate that period.”

Stressing that denial legislation can serve an important purpose when necessary, Abbott urged parliamentarians to undertake a thorough review of the need for and purpose of such a law.

“If the National Assembly deems it necessary to issue a law against hate speech, there should be a wide consultation amongst people, lawyers, judges and civil society to ensure it complies with Cambodia’s human rights obligations,” he said.

“Why does this need to be done so quickly – within a week or so?”

Additional reporting by Vong Sokheng