Yeah, shitty isn't it when you have to really rely on your bloody personal document named as identity card/visas just to stay healthy mentally and spiritually. Have you ever been in this situation; rush by police in a gig, they demand your filthy IC and thats it, you feel like some part of your body were taken away and you really think that you need it back. Well that's the system in Malaysia.
I don't know bout other countries what does the cop do or what type of document do you bring with you, it might be different, ok here my point. If my IC is not there with the cops; I will, without hesitation run away as hell, as fast as I can when i got the chance.But if my IC was there with the cop I feel like theres no point running away.
I don't know much about what happen if you're caught in a demonstration/protest, as I've never been in such situation. But here are my small (probably cliche, old, vintage ,crap) idea; bring a photocopied fake IC!! well you figure out yourself how, as far as I know police won't mind if you bring a photocopied IC, so fake it out, give to them and run when you get a chance,I believe there are usually plenty of chances to run on the way they taking you to the black maria. So try it at your own risk.especially those under 18, cops really dig you guys hahah but if too many do it the trick won't work anymore lah, so avoid getting caught/fight as hell/surrender. choose your destiny.cheers!good luck in the battle.
(Picture originally by Strike vs Freedom taken from Flickr)