system
Given the following post, respond as if you're commenting on Reddit:
human
[My Hero Academia] How do they regulate people with inherently dangerous Quirks?

In a society where 80% of the population is powered, what systems are in place to deal with people with Quirks that are dangerous or have the potential to be seriously misused?

I mean, just having a bunch of hero agencies around can't do much if someone whose quirk is uncontrollable killer sneezes is walking around in allergy season. Even Shinzo's brainwashing power is incredibly dangerous considering how badly The Purple Man misused his similar power in Jessica Jones.
gpt
You may be underestimating how many "heroes" are running around trying to make a name for themselves. Even if a dangerous quirk shows up in an uncontrollable way it would be a short lived crisis. Some hero will jump in to either contain the threat or at least minimize damage while a better suited hero is called to the scene.

As for how to handle it after that, temporary confinement and then release. The entirety of this society revolves around quirks, so finding a tech solution to even the most extreme of quirks is likely to be a short venture.