Punishment in primary schools, are there generally agreed principles about this?

[Longstocking2]

I imagine there would be rules like appropriateness, the punishment being proportionate, the child being spoken to alone about the misdemeanor, and the punishment happening reasonably soon? Is that the case in most schools?
My ds's teacher is being, imo, very heavy handed with ds and it's infuriating me. I always try to support the teacher to ds, her authority is really important but gratuitous punishment is counter productive imo.
I don't want to talk to her about it because she can be arrogant and defensive and it may be worse for ds in the long run.

Schools should have a consistent behaviour policy. Of course, different teachers will interpret it differently. But, the head should then ensure consistency.

What did he do and what was his punishment?

Schools should have a Behaviour Management or Discipline policy. It might be worth asking to see the poicy if you are concerned the teacher is being heavy handed. We have a progression of punishments,
i.e.

1. Warning
2. Final warning
3. Consequences:

a) missing a couple of minutes of playtime or golden time, b) loosing special priviledges c) go to dep or head, miss all of playtime, d) parents called, etc. for more serious issues) But if children are frequent "offenders" we do jump the lighter ones and move straight on to higher ones. If they have hurt someone they often use missed playtime to write a sorry letter or card