Anarchangel has had some thoughts he's posted on Facebook, and he also linked to this piece. Seems to cover things nicely. I'm going to borrow three parts:
The bigger mistake, in my opinion, was made by Officer Yanez. He
appeared to panic when confronted by the fact that the driver he stopped
was armed and didn’t seem to be paying proper attention to his verbal
commands. He probably didn’t need to shoot Mr. Castile, but I feel
reasonably certain that the officer felt that he had no other option.
That is the predictable result of poor training, possibly combined with
poor hiring practices on the part of Officer Yanez’ agency. People
prone to panic should not be hired as cops. All cops should be given
quality force on force training so that they know how to handle
incidents like this without reflexively firing their weapons in abject
fear. Unfortunately, both problems are likely to persist in the face of
ever-shrinking government budgets.
On being an armed citizen dealing with cops,
It’s sad, but it’s probably safest for the armed citizen to assume
that the cop will be poorly trained and might get scared at your
notification. Do everything possible to keep things calm and avoid
making any potentially threatening motions or statements. There’s no
guarantee that this will keep you safe, but it’s the best advice I can
And on cops dealing with armed citizens,
If you are scared of legally armed citizens with CCW permits and you
freak out because someone has a gun, you simply aren’t confident in your
own abilities. That’s a huge problem. When you aren’t skilled and
confident, you get scared and you over react. Freaked out cops don’t
make good decisions. When cops don’t make good decisions, they end up
on the national news.
And someone winds up dead, crippled or in a hospital when they shouldn't have.