Bullet proof clothing typically covers the chest area and wearing it doesn’t mean you won’t be injured. As a police officer’s primary job is to diffuse a crisis situation, not “kill every suspected perp”, I see minimal reason a bullet proof vest on the perp would impact the police significantly.

Try getting shot, especially multiple times, wearing a bullet proof vest and you’ll understand completely why my opinion isn’t out of line.

What is it like, for those of us who don't have guns and bulletproof vests on hands to experiment? Does it knock the breath out of you? Would it bring you to the ground?

3A Body Armor vs.12ga. Buckshot and Slugs https://www.youtube.com/watch?v=4qSVOZfp3R4

3A Body Armor vs. Pistol Caliber Carbines https://www.youtube.com/watch?v=ia1k1Zg4l2A

Handguns are handguns. Rifles are rifles.

You feel the entire kinetic energy of the bullet with a vest, the bullet just doesn’t go through. Imagine driving a truck at 100mph into a sturdy concrete wall. Similarish outcome.

I believe it would take a person down and possibly kill them. I've been told police are taught 2 to the chest 1 to the head.

From my quick googling, a great read: "...Among the accounts from those who have experienced being shot while wearing a bulletproof vest (and lived to talk about it), there is one consistent analogy to describe the feeling: being hit with a baseball bat. ..." http://www.ponderweasel.com/shot-wearing-a-bulletproof-vest/

"Getting hit hard in the chest by a big blunt concussive object"

I think the reason is similar to what was shown for seat belts:

When you know you are protected you take more risks. If criminals can protect themselves they are probably more likely to use violence in the first place.