The arrests of more than 50 pro-democracy politicians in Hong Kong mark Beijing’s most sweeping attempt yet to redefine the "One Country, Two Systems” arrangement that governed the former British colony’s return to China 23 years ago. They are a challenge to both the incoming U.S. administration of President-elect Joe Biden and the European Union, which concluded an ill-timed investment deal with China only last week.

The opposition figures, along with an American lawyer, were detained for organizing and participating in an informal primary election in July, which Chinese agencies and the city’s leader condemned at the time as an "unlawful manipulation” of the city’s election system and a potential violation of the national security law that took effect the same month.

Let’s be clear. The primary that authorities have labeled subversion is simply democratic politics as it has been conducted in Hong Kong for more than a decade. The purpose of the exercise, in which more than 600,000 Hong Kong people voted, was to select the candidates with the best chances of prevailing in last year’s planned September elections for the city’s Legislative Council. The opposition camp’s real crime is to have come too close to winning.