Regardless what you think of the Occupy Wall Street movement (or whether it will ever get its act together and come to mean anything) this was not an escalation of force scenario, this was civil disobedience and passive resistance. If peaceful protesters must be removed you bring in enough officers to pick up each one and remove him or her to the paddy wagon. If anyone actively resists then the officers making the arrest apply sufficient force to proceed. At least that's the way it's suppose to go ever since the Birmingham cops quit using German Shepherds and fire hoses on civil rights protesters and the Ohio National Guard quit using live ammo on Vietnam war protesters. Anything less than TLC is a win for the protesters and they know it. It's important that those with responsibility for public order understand it too. In this case, regardless whether or not the force applied was strictly legal or within department guidelines, the techniques applied and video collected played precisely into the hands of the protesters. The incident represents a massive fail on behalf of those in authority.
O.C. sprays - like Tasers - have undoubtedly saved many criminals from serious injury or death due to the baton blows, choke holds, or gunshot wounds used to subdue suspects in the days before these non-lethal force alternatives were developed. Likewise, their use reduces injuries to law enforcement officers and is safer for the public. But non-lethal does not mean harmless, and force is still force. And this force is being applied on our behalf. We had better be sure what objectives we wish to achieve. The Occupy movement couldn't have stage managed a better PR coup had they tried; was that the objective?