Shēnwéi jǐngchá què tānwū shòuhuì, zhēnshi zhīfǎfànfǎ.
A police officer taking bribes - knowingly breaking the very law he should uphold.
Tips
history
From Wu Jingzi's 《儒林外史》 (Qing dynasty): 好僧官老爷！知法犯法！ - 'Some Buddhist official you are - knowing the rules and breaking them!' A satirical jab at clergy who flouted their own precepts.
usage
Especially pointed when the offender is a judge, police officer, official, or someone in a position that requires legal knowledge. Implies extra moral fault beyond the offense itself.
