Comment by AnthonyMouse

The way authoritarianism work is they pick some enemy to rally against and convince people that the ends of stopping that evil justify the means of becoming evil. The problem with this is that it can garner 51% support within the population for temporary periods of time, so you need a system that can prevent it even in that environment. This typically means that violations of fundamental rights should require significantly more than 51% popular support or require changes in public sentiment to stick for a period of time before they can make foundational changes (e.g. only a third of the US Senate being up for election every two years).