Who should be the one to raise a problem — the principal or a peer?

The person with the least authority who can address it effectively. That's the principle, and it changes how you think about accountability in your building.

If a team member is consistently late to meetings, the team leader should address it before the principal does. If a colleague's classroom management is disrupting the hallway, the neighboring teacher has standing to raise it before it becomes an office referral. When peers hold peers accountable, problems get addressed earlier, at lower stakes, and without the weight of positional authority that makes everything feel like a formal action.

That doesn't mean the principal never steps in. It means the principal isn't the default first responder for every interpersonal issue. Building a culture of peer accountability reduces the principal's burden and creates a more professionally mature organization.