So my buddy/coworker who lives in a seaside Southern California city sees a dude going through unlocked cars in his neighborhood. Buddy calls the guy out. Dude challenges him and flips out a knife.
Well buddy goes "Oh crap, my gun is inside," but does pull his own knife and says "You call that noife?" Kidding, he said "Bring it." Suspect beat feet. Buddy is already dialing 911.
Anyhow a captain from craptown PD calls him up and "blah blah blah" next time just be a good witness. Sound advice to avoid a knife fight, right? But on the other hand, he does have a moral responsibility to say something as well as (one could argue) a duty to.
Also, my buddy was hoping an officer was in the area (but no, probably dealing with a raving homeless derelict or booking a drug addict into jail for 11550 for the 347th time this week).
Other buddy agrees, however, his attitude is...much saltier. Essentially: "Captain, I respect you but you don't know more than me so save your energy and unf--k your state so citizens don't have to step in AND THEN get a lecture about civilians/off-duty dealing with mass low-level crime."
Note: this an adaptation from my non-fiction book Suburban Warfare: A cop's guide to surviving a civil war, SHTF, or modern urban combat, available on Amazon.