ADULTERERS in Cambodia could get up to a year in jail, after the prime minister, Hun Sen, used his big majority to push a bill banning extra-marital affairs through the lower house of parliament on September 1st. The opposition's howls of outrage were louder than they had been two days earlier, when another, more worrying measure was rushed through, curtailing parliamentarians' right to speak without fear of prosecution. That was possible because the restriction on lawmakers' immunity was wrapped in a bill granting them pensions and other perks, which proved irresistible even to some in the opposition.

In a country where many married men keep mistresses, enforcing marital fidelity seems hopelessly impractical. Under Cambodia's murderous Khmer Rouge regime in the 1970s, adulterers were executed—but even that discouraged the practice only briefly. One possibility is that Mr Hun Sen is seeking to discipline his Cambodian People's Party (CPP) and its coalition partner, FUNCINPEC. He is said to have become irritated at ministers arriving at official functions with their floozies instead of their wives.

The president of the lower house, Heng Samrin, a CPP man, argued that the new law would cut Cambodia's rampant corruption, since “if a government official has many wives or mistresses, he will become greedy for the state's money.” Intriguingly, Mr Hun Sen's information minister, Khieu Kanharith, normally a faithful parrot of the official line, said the adultery ban was going too far: he told a local newspaper that “a little extra-marital activity can be a beneficial stress-reliever”.

However, the adultery law was probably aimed specifically at undermining Prince Norodom Ranariddh, FUNCINPEC's leader, who is often seen accompanied by a dancer, rather than his wife. The law was passed shortly after the prince returned to Cambodia after five months' absence. By drawing attention to his private life, the government may hope to turn older, rural voters—FUNCINPEC's main supporters—against him. Mr Hun Sen no longer needs his coalition partner, because the constitution was changed earlier this year (at the opposition's request, oddly), so that governments no longer need a two-thirds majority in parliament to remain in office, just a simple majority. But it makes sense to damage the prince's reputation, so he would be less useful to the opposition, were he to join them.

Whatever the motives behind the adultery law, it is unlikely to be applied fairly, like most Cambodian laws. Nor is the other hastily-passed measure, stripping parliamentarians of their immunity if they say anything deemed to damage “an individual 's dignity, public order, social customs or national security”. This contradicts the constitution, which says lawmakers may not be prosecuted for opinions aired while doing their duty. The opposition is appealing to the Constitutional Council but, like other institutions, how independent it is from the CPP is unclear.

Last year, the main opposition leader, Sam Rainsy, fled into exile after lawmakers voted to suspend his immunity so he could be prosecuted for accusing the prime minister of orchestrating violent assaults against his opponents. In February, Mr Sam Rainsy returned, having agreed to recant his allegations and be pardoned.

Since then, the opposition has tamed its habit of making disturbing but unsubstantiated claims. But the government now faces allegations of officially-sanctioned murder aired by a former police chief, Heng Pov, who has gone on the run after being charged with killing a judge. He claims he is being framed for refusing orders to kill from Hok Lundy, the prime minister's feared internal-security chief. The fugitive policeman was expelled from Singapore and may be in Malaysia. Whatever becomes of him, the chances of his allegations being properly investigated seem rather slim.

Killings and disappearances of anti-government figures seem to have stopped in the past year or two, notes a diplomat in Phnom Penh. That is some sort of progress. Mr Hun Sen now seems to have little need for such harsh tactics. His new laws make it easier for him to cow his opponents, actual or potential, by threatening them with prosecution—either for their loose tongues or their loose living.