We make a bargain with our governments. We pay taxes and expect a set of government services in return. And in return for a guarantee of some measure of security, we grant the government a monopoly on legitimate violence. In theory, then, we forswear mob rule and paramilitary organizations, we occasionally accept the death penalty as an appropriate punishment, we delegate the responsibility to declare and prosecute war to our legislative and executive branches, and we put guns into the hands of the army and the police.
Governments, in other words, kill on our behalf.
Read more here: Governments Kill | FPIF.