The best step starts from reruting guys with strong ethical behaviour.
Various other steps can be taken like all communication being scanned. There are places where email and all information going out is scanned. The desktop/laptop does not have hard-disk or the access is restricted and all work is on network folders, even when working from home, one has to get connected to internet. The offline work gets synchronized. The USB and drives are disconnected.
The other policies are to provide access only on need basis.
These will only slow down and hinder to some extent, but is one is very determined then he would find ways to get around this.
The other way is if the code is really very important, then have the idea copywrite protected legaly.
