Simply there are two types of weapons, those that could cause a fatal injury and others that don't. The example appears in those weapons used with other species when the idea is to capture them without producing more than a temporal sleep.
A human of course also enters in the same group of species that interact with this kind of sedatives, thus the final result would be equally effective. Thinking in police affairs, or government security in general toward citizens, the use of fatal weapons empirically speaking is not necessary in the most relevant part of the everyday life.
The business of weapons, buying or selling, promotes insecurity as places dangerous devices in the hands of a being that in statistical terms is not completely stable and experiences multiple conditions that create the possibility of a non rational psychological approach. Wars normally end with thousands of victims or much worse. When a form of instability emerges, with fatal weapons the consequences are usually tragedies. The danger escalates with the destruction capability of the weapons and in the present time the reality of thermonuclear devices seems the worst imaginable case without solid solutions but fortunately multiple tries.
Different countries are spending more money in military than in health or education. The numbers in terms of global resources destined to this kind of area are against ethics, humanity, in the same international scenario where poverty causes malnutrition or death, or the environmental crisis. But the sad reality is that wars were practically cyclic during centuries, creating horrendous pages of history with critical conditions that are even suspected to be the origin of catastrophic pests, very difficult of being controlled at that time.
The new generations should see these lamentable methods as an evidence of primeval behavior, where the brutality frequently won against the mental processes that differentiate humans from other species. Any population shares the same chromosomes with minor differences by the way, science or the knowledge in general must stop those irrational arguments of superior races (or the perfect gene that could draw a smile in who studies them), mysticism or people thinking in being different as a sign of nationalism.
To understand what a human life implies is fundamental, with a potential span of more or less 120 years, capable of achieving multiple skills, modify his/her conduct and providing valuable help, so who could ever think in being the cause of stopping one? That kind of decision doesn't seem to be accomplished by aleatory genetic codes, and when they do it's necessary to note that this path looks like to believe in having comparable responsibilities with mighty Nature, the superior endeavor that created every life form and plans every possibility. Evolution is not an afternoon caprice. It was demonstrated that a human (not all) can believe in anything without technical backup, from Earth as static center of the Universe to alien abductions but there's only one reality, and it could escape from us due to the limitation in intelligence of any brain that must be enclosed in a finite space.
An important element to increase overall security for everybody should appear avoiding fatal weapons and using others without the objective of killing or severe injuries. A fatal weapon creates a death threat and that kind of coercion doesn't really fit within an ethic society since there are other alternatives.
An idea is the policeman with two weapons, one with sedative intentions and another for rare extreme situations. This alone could save numerous lives.