Notice the report says "single most critical factor" not only factor,
True, and some will opt to maximize the most significant factor, while others are more comfortable with a compromise between different factors. It's hard to say with any certainty which is truly better, so while we can all try to make our case here, ultimately we should go with whatever we're most comfortable with as individuals.
and "for law enforcement use." not for everyone.
What's the difference, though? Isn't stopping the threat the common goal? If you're thinking of the requirement to penetrate hard intervening barriers, then that is a separate issue--the standards set by the FBI report are for the depth of penetration into simulated flesh (e.g. calibrated ballistics gelatin), taking into account only intervening body parts such as limbs as well as the various angles at which a bullet can enter a human body. Separate tests are done through various barriers for evaluation when ammo is to be selected, but the acceptable range of penetration depth they give, 12"-18", is for what happens afterward in simulated flesh, and to my knowledge does not include the thicknesses of the barriers. In other words, they don't give a preferred depth and say that this will be enough to take into account various barriers--they actually shoot bullets through real barriers and into gel, and then measure penetration. And after all of that has been said, ironically with JHPs you generally get more penetration into flesh after going through a barrier, usually because the bullets don't expand quite as much, if at all.
In my opinion, JHPs in .380 are what I want to carry. Yes, if they expand (which they may not at that velocity) they will have less penetration but they will also make a more damaging wound than a FMJ. Your goal may be to "fully penetrate a human target" mine is not. If you don't have faith in the .380 as a caliber than don't carry one.
I would feel adequately, though perhaps minimally, armed with a .380 ACP pistol. And of course your goal with regard to terminal ballistics doesn't have to be the same as mine. Many people even prefer JHP bullets specifically because they're not likely to penetrate all the way through a human target. I think this makes them less effective overall, but if that's what people want (for a safety factor), then that's what they should use (as long as they're aware of the tradeoffs they are making).
BTW. I find it interesting that so many people read the FBI reports and conclude they should carry FMJs when the FBI didn't come to that same conclusion.
The FBI report emphasized the importance of adequate penetration, and with JHPs .380 ACP does not quite make even their lowest standard. Not that there are any hard thresholds by any means, but that only implies that even a full 12" of penetration is marginal rather than preferable. The report also says "regardless of whether it expands or not," which I interpret as meaning that they'd rather be able to poke a hole in a vital structure at all than have a bullet stop short due to a lack of penetration (which is exactly what happened in the notorious 1986 Miami shootout). For calibers such as .380 ACP and human-sized targets, it means that FMJ is considered, at least by the FBI's standards, to be more effective. Nobody has to agree with them, but that's what they're saying.
With more powerful calibers, obviously JHP is the way to go, but I'd still look carefully at the terminal ballistics to find the best loads. The primary .40 S&W JHP load that the FBI currently uses, for what it's worth, gets 19" of penetration in ballistic gelatin through heavy clothing, slightly more than the 18" they consider ideal. If they used .380 ACP (which they don't, except perhaps as backup guns by individual agents), then I bet they would opt for FMJ for general duty (unless they could team with a manufacturer to get the performance they want from JHPs, anyway--all I get to do is pick from what's on the market). Not that they're necessarily THE authority on handgun ammunition, however--feel free to disagree with them.
I will give up a little penetration for a round that will likely produce a much more effective "wound" or crush path than a FMJ that has a notoriously poor crush path.
I agree that JHP rounds (and even flat-nosed rounds, for that matter) wound more effectively, but it does little good in a gunfight unless they wound something vital, and they may have to penetrate and wound a lot of non-vital flesh to get there--if they can get there at all--expending their limited energy and momentum along the way.
I agree with the report whole heartedly that I wouldn't choose it as a round for LE use. I hope we can leave it at that as the OP didn't try to start an FBI Ballistics discussion.
I don't wish to derail the thread either, but if some folks give what the FBI report says credibility--with regard to the topic of this thread--and there is disagreement over its interpretation, then it is a relevant subtopic. In addition, I'm still curious about the difference between LE and self-defense use. Is it what I covered earlier (barrier penetration) or something else?