Various forms of public assembly are limited and/or restricted by governments. But when demands for reform are not met, citizens will voice their discontent in a public demonstration such as a rally, protest and/or strike. Injustice such as an unfair election, a controversial government decision, a war, or a corporate action are typical triggers for public demonstrations. Though non-lethal methods such as tear gas, pepper spray and water cannons are used for crowd-control, they can still be dangerous and even deadly, and are criticized as tools of state-sponsored human rights abuse. Non-violent assemblies can quickly escalate into riots when police or other authorities are unable to impose proper crowd-control methods.
