From 1977 through 2015 there have been 1,422 inmates executed via the death penalty in the United States, which while regrettable, at least these victims were theoretically duly tried with an impartial jury and judge, permitted defense council as per Constitutional law, and were in due course sentenced to capital punishment as duly prescribed by law, with depending upon their particular circumstances also given the opportunity to appeal such a verdict. It can be said that of those given the death penalty and executed within the United States, that they probably were afforded a reasonable opportunity to defend themselves.
There are virtually every day in the United States, suspects, if even that, and criminals, no doubt, that are for lack of a better word, executed by law officers in their line of duty. By definition, none of these victims have been duly tried or convicted of whatever offense that they are alleged to have been involved in at that moment, and while there are specific rules in regards to the use of deadly force, it would seem, that those rules are permanently bent in the favor of law officers to do whatever that their discretion believes need to be done in these types of situations. While, there is no argument that officers of the law, should be permitted to meet fire with fire, it should however be recognized that their overarching aim should always be to protect and to serve their constituents, and that they should not be permitted to be judge, jury, and executioner of suspects and thereby become their own law, thereupon trumping and negating proper jurisprudence of this great nation.
The fact of the matter is that http://www.killedbypolice.net informs us that law officers killed 1200 people in 2015, nearly the same amount of people that have been executed via the death penalty over the last 40-odd years. Now, no doubt, the real world has some very bad people in it, people that put other citizens and police officers in harm's way, to which, one reasonable response by a law officer would be to engage that suspect in deadly fire. However, that is one response, but typically, although not always, there are alternate responses to deadly force that could be used or should at least be considered being utilized.
The one thing that cannot be argued about today's police force is that the weapons that they have in their extensive arsenal are extremely lethal, while on the one hand, that might be considered to be a good thing, on the other hand, deadly force, is not something that can ever be retracted, so that it probably would behoove police departments in general, to seriously consider other viable options other than the most deadly ones.
It is not easy to be a good police officer, nor is it easy to exercise proper restraint and discretion in situations to which things are chaotic, unclear, frightful, and dangerous. So too, it must be stated, that it is easy to second guess another person's decision, yet, quite candidly, true justice does not ever come at the barrel of a gun, or the end of a rope, or other lethal means, it never has, and it never will.