"One of the things that I trained in use of force was to physically stop an officer who's 'losing it'," Marcou told POLICE Magazine. "An officer who's 'losing it' is going to do damage to every officer there—and we've discovered that sometimes that'll be multiplied nationwide."
Marcou emphasized that the key to successfully intervening in what he calls "officer overdrive" is the prior agreement between officers that everyone on patrol should be trained to recognize a predetermined code word or phrase used to communicate with one another in order to keep everyone under control.
In the abovementioned incident, the officer who intervened seems to have acted according to her training, but there is the possibility that the key element of an agreed-upon protocol between all officers at the scene—a phrase or signal to the officer in danger of "losing it" that peer intervention is taking place—was either unheard or misunderstood by the sergeant, or simply didn't exist in the first place.
Without the benefit of the audio, it's all but impossible to say. However, it's clear hat the officer attempting to help her sergeant—specifically, to keep him from doing something that result in a disciplinary action for excessive use of force—became the target of the sergeant's ire.
This outcome was—obviously—sub-optimal for everyone concerned.