Yesterday I had the opportunity to witness something that most Scrum Master has to face. A situation arise in a team where the PO had ask a task to one of the team member, there fore bypassing the SM. Don't get me wrong self organize team is one of our goal as SM, even more that task was important enough for the PO to ask the team member directly!
The thing to remember is that each role in a Scrum team is important, and each role has to know their responsibilities. The whole team has to know the boundaries of the Scrum process. As a SM we have to educate people to the process and, most of all, remind them of the process when they are out of line. In that situation, the main problem is that some activities were planned for the whole team during the day. The fact that this team member was doing something outside the planned activities, disturb the team and even stop it's evolution. What the team member should have done was to tell the SM about this task ask by the PO. Even better, the PO should have talk to the SM about that task and planned it for the next sprint.
The PO has to work continuously with the SM and vice versa, they have to work for the same goal. The PO has to know that when the team engage themselves in a sprint he doesn't have the right to interfere with the team. If he wants to interfere with the work the team committed themselves on doing he has to discuss it with the SM (who should say no!). Whatever the reason, most of the time the work can be postpone to next sprint.
(I will discuss this at a later date, for this is a subject for a blog entry on it's own)
What I want you fellow SM to remember is that we should never assume that the team know the process or even theirs role. The situation I brought up in that blog happens to a team doing scrum for the past year and more. I personally think the we have to continually remind the team about theirs role (the PO included). We are the guardian of the process and we should always be ready for any intruder!