It brings knowledge, skill, and insight to bear in unpredictable ways. It involves making personal contributions, judgment calls, exercising autonomy, and individual solutions. It's about the courage to make your own decisions, to have personal input, following your conscience, even if those decisions are reversed later by a superior. Prudence, foresight, the ability to size up people, arguments, and situations. Tactfulness, tolerance, empathy, and being discreet are all forms of discernment.
Discretion is the opposite of standard expectations.
It's the privilege to go against the rules, disobey your superiors, be less than optimal or perfect all the time, all without degenerating the rules or eroding the trust between you, your superiors, or the public. Discretion is not doing as you please. The future of policing as a profession depends upon whether discretion can be put to good use. Sometimes the public wants nonenforcement, and other times they want strict enforcement. Police take adult complaints more seriously than those made by juveniles.