How about looking to the dozens of other western countries where the per capita killing of citizens by police is 25 times or more lower? Like Austria, where cops carry guns too but from 2000-2011 (12 years) there were a total of 12 police killings.

I find it fucking amazing and infuriating that my countrymen and women constantly take the position, "Well, we haven't done it in the US, so I guess it is not possible. No sense looking at the 100+ other countries that have solved this problem, because [fill in bogus reason like homogenenity, physical size, population, etc.]."