Two former U.K. judges have resigned from Hong Kong’s top court as the city continues a national security crackdown that has silenced dissent in the former British colony.

Lord Jonathan Sumption and Lord Lawrence Collins, who were former judges on the U.K. Supreme Court, tendered their resignations to the leader of the once-freewheeling Chinese territory, the city’s government said in a statement late Thursday night.

Collins, who began serving as a nonpermanent judge on Hong Kong’s highest court in 2011, cited political reasons for his resignation in what is likely to be seen as a blow to the reputation of the city’s vaunted judiciary.