What ideas can I discuss if 'Violence is never justified as form of public protest' in relation to the London riots.

I think that one line of logic that can be used with this
particular prompt is the idea as to how lawlessness cannot be tolerated in a social
setting.  This would advocate that if individuals revert to breaking the law, no matter
their motivations, society ends up crumbling fairly quickly.  For example, regardless of
what motivated the rioters, the city burned, property damage was huge, lives were
ruined.  The rule of law is what allows society to function properly, and once this is
discarded, there is little guarantee of what can and will happen next.  At the same
time, I am not really sure the rioters' desires, whatever they might have been,
overwhelms the damage caused to so many.  The business owners whose economic viability
became ruined by the London Riots did not shoot Mark Duggan.  The children whose lives
where endangered because of the fires caused did not shoot Mark Duggan.  The people who
saw their lives disrupted by the rioters did not shoot Mark Duggan.  One reason why
violence can never be tolerated as a form of public protest is because the people who
are impacted are innocent.  They had nothing to do with the source of the rioters'
anger.  They were "there" and because of this, their lives are ruined.  For this reason
alone, violence cannot be accepted as a form of social protest.