There's a 9th circuit ruling specifically outlining this pepper spray illegality http://caselaw.findlaw.com/us-9th-circuit/1332957.html
Assistant Professor of UC DavisThere must be space for students to assert their right to decide on the form of their protest, their dissent, and their civil disobedience—including the simple act of setting up tents in solidarity with other students who have done so. There must be space for protest and dissent, especially, when the object of protest and dissent is police brutality itself. You may not order police to forcefully disperse student protesters peacefully protesting police brutality. You may not do so. It is not an option available to you as the Chancellor of a UC campus. That is why I am calling for your immediate resignation.