Tear gas is banned in warfare by the Chemical Weapons Convention of 1993. In low doses, it can be relatively harmless, but police forces across the world, including our own, have a record of abuse and misuse of this potentially dangerous chemical.
Possible life-threatening consequences can occur from use of this method of crowd dispersal, such as blunt force trauma (from improperly deployed canisters), chemical burns, asphyxiation, and heart failure. This is particularly problematic for those who suffer from various chronic diseases, who could easily be caught in unrest accidentally.
Based on the inability to control the spread of the chemical and it's potentially lethal side-effects, the use of it against civilians should be banned and condemned by our federal and state governments.