With much of the world on lockdown, the coronavirus pandemic has chipped away at individual liberties everywhere. In more places, however, it is also being used as an excuse to weaken democratic institutions and oversight—an authoritarian slide that could endure once the current health emergency subsides.

In Russia, President Vladimir Putin this month pushed through parliament the removal of term limits, ensuring he could remain in power for life, just as the fear of the coronavirus has rendered public protests against these...