I'm generally of the view with "qualified immunity" that it needs to be outright abolished. But if you wanted a middle-ground option, you could make it an affirmative defense. What I mean is this: Require that, in front of a jury, the officer provides either a preponderance of evidence or clear and convincing evidence that it was within their discretionary authority, that they had reasonable fear, or whatever (enumerated) set of things. Define it in written law. Narrowly. Make them prove to a jury that they could not have reasonably been expected to behave otherwise given the totality of the experience, and that a reasonable person would have done the same.