Well past midnight one day this spring, three police officers pulled up to a nightclub where a man was stomping on a young woman lying on the sidewalk.

The officers stopped the attack and arrested him, according to a police report. It was the kind of assault police might encounter on almost any night in almost any city.

But one detail stood out to police officer Xavier Jimenez, who wrote the report: ¡°There was approximately 15 national guard members in the area on routine patrol who did not take any action.¡±