you can always modify your tattoos, you can't modify your face once it's identified. I saw a man literally draw a face on his face before attending a protest. He looked ridiculous but perfectly "defaced".

I've also read about some blackBlocs getting identified, where i live, through their shoes. Police photographed people before and after the movement and their shoes are used as identifying information.

There is always the oldBloc who put their faces and names behind their words and proudly struggle through unions.

it's already may 1st here. They will be out in about 10 hours. May the force be with them.