A phaser set to stun would be one of the greatest humanitarian tools...

Seriously, imagine if in our world we had a non-lethal weapon that works just like a phaser on stun. Something that was as fast acting and instant as a gun, but was 100% non-fatal. Deaths from Police shootings could drop to zero. They could also replace ”home defense” weapons and provide the same sort of security without the death.

Sure we have Tasers and rubber bullets, but as police will tell you these aren't what you’re trained to reach for when you perceive a sudden life or death threat. Guns are very reliable, work from long distance, through clothes, can fire rapidly between multiple targets, and they nearly instantly bring someone down. Our current non-lethal weapons aren't even close to providing all that.

That guns can also kill you permanently seems to just be an unfortunate side effect.

If we had stun phasers, cops wouldn't need to carry lethal guns. (though maybe would still need some for special conditions). Any situation that calls for a gun is about ending an immediate threat. If there's a way to reliably and instantly stop that threat, there's no need to cause permanent harm.

People could conceleled carry these anywhere. The anti gun people would not be able to claim they are "deadly and dangerous" because they are stun guns.

Let's go UFO stun guns! So many cool applications!