Related to "doing something wrong" and not being supported by any agency, California recently passed AB392, their "necessary force" law. The previous standard in CA (and the general standard across the country, inviting the federal level, and set by the Supreme Court) is that force has to be "reasonable." California changed that to "necessary" which implies that so-called lower levels of force be exhausted before moving to other options.

Suppose in my little tussle with the thief that I follow my training, as well as my agency's use-of-force policy, and apply force that is reasonable under the circumstances but not "necessary" under the state of California. They might try to charge me. My agency may or may not stand by me since enforcing local laws is not within my scope of authority, and no agency is excited to sign itself up for a lawsuit (the agency's lawyers represent the interests of the agency, not you). Plus, as a federal agent I could be opening myself up to a lawsuit (definitely a Bivens claim, maybe a 1983 even though I'm federal--I don't really want to blaze new case law at any rate). I carry private liability insurance but am in no hurry to file a claim on it. There's so many ways things could go badly.

Look--my responses (especially the second one) were aggressively snarky. But there's a great deal of value in the phrase "discretion is the better part of valor." Anyone who wants to jump in and be the hero should think long and hard about all the ways it can go wrong. He can take a swing with one of those heavy Milwaukee tools and send you into a coma or kill you. You can draw your surprisingly powerful .380 (sorry, couldn't resist) and be completely legally justified, but find yourself on the end of a lifetime of lawsuits, public opprobrium, and psychic and emotional scars. Are those consequences worth stopping a couple hundred dollars worth of shoplifting? Especially when, if you're able to apprehend the guy, he may get a slap on the wrist at most (depending on jurisdiction)?

Believe me--there's a reason I left behind a pretty decent 10 year career in finance to do what I do now. No one wants to "bring people to justice" more than me--if CA gave me peace officer status, there's a good chance I'd spend some of my downtime pulling over all the dumb drivers, explaining their stupidity, and then letting them off with warnings, just because it's so frustrating to see. But unless it's literally your job (local police or maybe loss prevention) there's a multitude of ways that intervening, even when it's objectively the right thing, can go wrong.

I hope anyone who actually thinks they would do something at least considers that there's a whole host of potential problems that can come from it. IMO if life and limb aren't involved, you're better off being a good witness and leaving it to the men and women for whom it's their actual job.