Dealing with a bad apple
Clarify what the rules are, get them signed off by the employee. Fire him in case of a serious breach, if he is not indispensible. If he is a lynchpin employee, set up a short probation period. Provide extra supervision. Don’t let him repeatedly excuse bad behavior. Hire in the first place not only for performance but also for compliance (predictive tests are available measuring reliability and ethical maturity). Keep careful records of how you deal with the problem employee, especially one who has any attributes protected by the law, for example disability. Be covered by showing why you weren’t able to accommodate that employee and had no choice but to fire him.