Heckler’s veto - Definition from the Hotspot Shield Encyclopedia
This phrase has a dual meaning. In legal terms and concerning law, a Heckler's Veto is where a speaker (at a political rally or demonstration for example) is forcibly prevented from performing their speech in order to stop civil unrest and the perceived black lash from protestors and onlookers that their speech may cause.
If a particular speech or demonstration has the potential to cause unrest, a government or local authority may feel it is in the public's best interest to prevent the speech from happening. In general terms, a Heckler's Veto is where a person has the right to heckle a public speech without drowning them out, and has the potential to stop the speech without resulting to intervention from the authorities.