Pepper Spray: Assault With a Deadly Weapon

This article from Scientific American points out the dangers of this highly potent, weapons grade chemical spray being routinely used on nonviolent protesters. It is potentially lethal when sprayed down the throat.

Assault With a Deadly Weapon

Note that the pepper spray you can carry in your purse is in the range of 2 million Scoville Heat Units. The industrial, weaponized grade being used by police is more than twice as powerful. It is more than 100 times more powerful – let’s say blistering – than Cayenne pepper.

I wonder if an attorney might be able to tell us, at what point does this rise to the level where such an attack against nonviolent protesters might be prosecuted as battery or attack with a deadly weapon? Or are law enforcement officers exempt from such charges under all circumstances while in uniform?