If someone is politically engaged enough to get arrested at a political protest, it seems like a reasonable assumption that they would be registered to vote

How to radicalize a lot of smart people in a very short period of time

Can you narrow it down to a specific country? Licensure and regulation will likely vary on a per-country basis. Assuming you’re not in the US based on the global availability stipulation, but if you are, psychologytoday.com is a good place to start.