Steven Levitsky and Daniel Ziblatt in their book How Democracies Die: What history reveals about the future, tell us about the historical collapses of democracies.

1. Rejection of democratic rules

2. Denial of the legitimacy of political opponents

3. Tolerance/encouragement of violence

4. Readiness to curtail civil liberties of opponents, including the media

Democracies die in three stages: the election of an authoritarian leader, the concentration and abuse of governmental power and finally, the complete repression of opposition and citizens.