Since the outbreak of the coronavirus pandemic, some democracies around the world have used technology to avoid having to impose draconian mass quarantines that were common earlier this year in China. That’s reassuring — and it’s also worrying, because the very strategies that can help fight a plague can also be abused once it’s over.

Consider Taiwan, where an “electronic fence” allows local police to make regular phone calls to everyone who is home under quarantine; if the citizen doesn’t answer or the phone is out of power, police come to the home within 15 minutes.

In South Korea, the government constantly updates a website that tracks the movements of people who have been infected, and issues alerts to the mobile phones of people in the geographic vicinity of an infected citizen.