Heretical question: Why do public school teachers need tenure?

[mike_c]

6. historically, to protect academic freedom....

Doing so comes in many forms, but ultimately it's to protect teachers from being fired because of what they teach. The irony is that K-12 administrations have effectively done an end run around academic freedom by seizing control of the curriculum, then dictating what teachers will teach. Still, tenure protects them from crappy administrators, and administrative crappiness is rampant, all the way up to local and state school boards and other administrative bodies, many of which are staffed by people who have zero teaching experience, and often have agendas in direct conflict with good education.

As others have pointed out, tenured teachers can still be fired for cause and they can still be laid off. They're simply guaranteed due process if they have tenure.