As evening fell yesterday, Hong Sok Hour, a senator in the Sam Rainsy Party, was in hiding but still protected under the Cambodian constitution’s rules on immunity.

It’s a status few believe will last. Earlier in the day, Prime Minister Hun Sen had called for Sok Hour’s arrest on the grounds he committed treason by posting “fake” treaties related to the Cambodia-Vietnam border and an accompanying video to social media site Facebook.

But despite no arrest taking place yesterday and the postponement of a senatorial meeting on the issue, all signs point to the Senate, a body dominated by the ruling Cambodia People’s Party, moving quickly to strip Sok Hour’s immunity.

The threat of immunity being abruptly removed is a familiar one for opposition lawmakers, but also a worrying one to observers who believe the seemingly arbitrary nature of how and when it is carried out throws the authority of the nation’s charter into doubt.

Article 104 of Cambodia’s constitution states: “Senators shall enjoy parliamentary immunity.

No Senator shall be prosecuted, detained or arrested because of opinions expressed in the exercise of his/her duties.

” In fact, senators can be arrested only with the body’s consent, unless caught “in flagrante delicto”, or in the midst of committing a crime.

Article 80 uses the same language with regard to members of the National Assembly.

Opposition members have seen their immunity stripped in the past when the CPP used its majorities in both houses to effectively vote away the right: it happened to both CNRP president Sam Rainsy and lawmaker Mu Sochua in 2009.

Just two weeks ago, Hun Sen warned seven CRNP lawmakers charged with leading an “insurrection” in July 2014 – of whom Sochua is one – that their constitutionally mandated immunity would not protect them should a fresh round of summonses call them to court.

“When I was accused in 2009, my immunity was lifted because CPP had 90 seats,” Mu Sochua said yesterday.

“In 2014, our accusation, arrest and detention [happened] without [the] lifting of immunity.”

Lawyer Sok Sam Oeun said Sochua’s 2009 case demonstrated how easily immunity could be lost when unclear legal language prone to unfair interpretation – such as the “in flagrante delicto” clause – weakens the judiciary and the constitution.

“In Mu Sochua’s case, if you look at the charge, it was defamation and there was no jail. It’s a petty crime, but immunity was still revoked,” he said. “When the judiciary is weak, laws should be more clear. The judiciary can be manipulated by powerful people.”

For former Constitutional Council member Son Soubert, a longtime royal adviser, such seeming disregard for the rule of law is a worrying sign for Cambodia’s fragile democracy.

“Both [legislative bodies] are not independent, since they are ruled by the same party,” he said. “In this sense, it’s become political, not constitutional.”

Human rights worker Billy Tai said the unfolding case shows that the immunity clause is fairly conditional in practice.

“The immunity is certainly not absolute, but only a ‘qualified’ immunity that can be stripped under certain circumstances,” he said.

“However, the fact that Hun Sen is calling the shots with complete and fairly blatant disregard to the process of the law is very concerning from the democracy perspective.”

Still, Sochua maintains that such manoeuvring by Hun Sen will only undermine his party ahead of the next elections.

“If [the] CPP continues to threaten opposition MPs with arrest, detention and lifting of immunity, it only backfires, because they can’t change the constitution nor can they give themselves extra seats,” she said. “The people are now watching the situation very closely, and social media works faster than the pro-government media.”