In a perfect world, no-tolerance policies for persecuting behavior would always work. While you should have a no-tolerance approach, you also have to understand that things will go on, and that passive-aggressive persecution is also a problem. Competition between two team members can wreak havoc on your project. Imagine for a moment that one team member, Bill, has been with the company for years and hopes to get a promotion. On the other hand, Joe has just started, and started in a higher position than Bill did. Now the two are in your team and they constantly try to one-up each other. The problem? They wind up making mistakes, and the work environment has a lot of tension. Don't allow this sort of competition, and don't instigate it. Treat all team members equally.