Cambodia observers said this week that the country could learn a lot from the current uncertainties in the United States since the election.
The legislation was passed by a unanimous vote of the ruling in the National Assembly amid an opposition boycott of proceedings.
Kim Sok was sued by Hun Sen following comments he made during a Radio Free Asia interview earlier this month.
Opponents accuse Hun Sen, a former Khmer Rouge guerrilla, of unfair maneuvering to try to retain his three-decade grip on power.
Oeuth Ang claimed he killed Ley over a $3,000 debt, but evidence has mounted to support the widely held belief that the killing was a politically motivated assassination.
The political landscape has been sharply altered by Sam Rainsy’s resignation as head of the opposition.
The senators say they wrote as friends of Cambodia, who wish to see a strong relationship between the two countries but who are troubled by the increased social and political turmoil in Cambodia.
Kim Sok told VOA Khmer on Sunday that he had expected to face harassment from the ruling party following his comments.
Most recently, the Sei Ha page published audio recordings purporting to show key members of the opposition Cambodia National Rescue Party discussing sex acts.
The proposal was rushed through parliament amid an opposition boycott of proceedings in response to ongoing political tensions and legal proceedings against its leadership.