Why are policemen generally required to first attest to being and remaining uncommonly virtuous, (even when off-duty), as a primary duty, rather than being mainly valued for their relative skills in the tasks of policing? Policemag.com's William Harvey writes:
As you apply to become a police officer or deputy, you must meet state and agency eligibility requirements. You'll also need to pass a thorough background investigation.
The background check ensures applicants with criminal pasts or current involvements are filtered out. So if you have a tawdry background, you need not apply.
It seems like making personal virtue primary might tend to maximize hypocrisy and corruptibility, as it will select for liars, (who claim to be virtuous), and the naive and oblivious.
What's the evidence that background checks and oaths are useful in this field? As opposed to letting anybody join up, and regularly winnowing out those who do a bad job...
The premise here is that good policing begins with one police officer who does a good job, and builds from there. That is, an officer who ably selects what to enforce sensibly, isn't paranoid, enforces laws impartially, doesn't slack off, avoids corruption and on-the-job deviancy, is not a reckless driver, and where violence is needed quietly shuns personal inefficiency and theatrics.
Often the main thing with selecting a job candidate is that the job be done well, and the main and practical distinction between the quality of separate workers is how well they do a job. Not who they are, where they're from, not their credentials, not their prior history, etc.
For example, given a choice between hiring two builders: an adulterous boozing reprobate who builds excellent houses, and a churchgoing paragon of virtue who builds houses that shake in the wind; many people would rationally prefer the reprobate.