A post inspired by 1.00 FTE:
Makes the obvious point - any truly bad behaviour should be addressed specifically with the given person. Otherwise you end up with gargantuan employee policy documents filled with items best left to local law enforcement.
The question then becomes, where to draw the line? I also think we can apply this principle to the grey-areas - the smaller infractions that, if policies are created, become annoyances that the rest of the staff must deal with.
I've been here before... company-wide policies on email, facebook, draconian time-clocking... generally only instigated when some young intern has done something stupid, so everybody else has to suffer for his/her bad behaviour.
Sure, if somebody abuses your trust then punish them, or fire them, or put them on probation or whatever you need to do. but changing a policy for the entire company is overkill. Especially when it degrades the previously open and enjoyable culture that you spent so many years developing.
Don't let the actions of a single individual degrade the trust that you give to your other employees. Trust is hard-won and easily lost, for sure... but it's also an essential component of a happy workplace. People don't want to be treated like they are children - and will find it stressful to be constantly nannied when they are capable of looking after themselves.
With a nod to the fact that some people *do* need supervision, try to trust your employees to at least act like the adults they are. After all - people try to meet your expectations... whatever they are.