How exactly this order is maintained by police, however, is less clear. In recent years, police agencies have insisted they have no legal obligation to directly intervene to protect people from threats posed by criminals. The courts have agreed.
Having abandoned the "protect" part of "to serve and protect," the police have retreated to the claim that their real role is simply to "enforce the law." This "enforcement" presumably would include investigation of crimes and arrests of suspects.
According to the most recent FBI "Crime in the United States" report, only 45 percent of violent crime lead to arrest and prosecution. That is, less than half of violent crimes result in what is known as a "clearance" of the crime. Property crime clearances are much worse. Only 17 percent of burglaries, arsons, and car thefts are "cleared."
Among violent crimes, homicides experience the highest clearance rate by far, at 61 percent. Aggravated assault comes in at 53 percent, and rape at 34 percent.