You can never do this 100% reliably, but depending on how important it is to you, there are measures that can be taken. To go to the complete extreme, you coul

You can never do this 100% reliably, but depending on how important it is to you, there are measures that can be taken. To go to the complete extreme, you could employ someone to shadow every one of your current employees, and report to you if they break any of these rules. At the other extreme, you could issue a memo saying "Don't let me catch you doing any of this stuff, which will make you more profitable and earn you a bigger bonus, hint hint." In between turning a blind eye and adding ridiculous amounts of oversight, the CEO can make very clear what is and what isn't acceptable, what the penalties are for employees who break these rules. S/he can also instigate appropriate oversight to make it more likely to catch offenders. Like I said at the start, this can never be 100% reliable, but it can cut down the rate of offence a lot. [edit] tl;dr : If it is important enough to you, you'll find a way to ensure it doesn't happen.