On 9th August 2014, unarmed 18 year old Michael Brown was shot by police officer Darren Wilson in Ferguson, Missouri, sparking social unrest that continues to this day. Here is a petition to prevent police misconduct.
This has been going on a long time. I saw lots of unnecessary use of violence by capitol police during the protests in Madison a couple years back. They even put there hands on an 8 year old child trying to follow them well they arrested his mother.