Teachers, as wahwah says have had the power to restrain children for years- in fact, by doing nothing, ie not physically intervening in a fight, or fetching somebody who is willing to physically intervene, you can be sued for negligence. Any 'no touch policy' is erroneous, and leaves children vulnerable and staff at risk of litigation and dismissal.
I am a teacher, and train other teachers in positive handling (restraint). I have taught in mainstream, SN and EBD settings. The problems arise when teachers are not properly trained to physically intervene- not only do they not know how, but do not know when it is appropriate to do so; and when it's not. Is it appropriate to physically prevent a child leaving a classroom? Sometimes, yes. If they are going after another child to beat them up for example. If you believe they will harm themselves or others, then yes. Because they didn't follow your instruction, then no. Deal with it later.
The legislation needs to be clarified. Presently, a teacher can restrain a pupil if:
-A child is injuring others
-A child is injuring themselves
-A child is damaging property
-A child is behaving in a way that is likely to disrupt good order.
Any physical intervention taken must be reasonable, proportionate and necessary.
This means that if a pupil is charging at another holding a knife, you are justified in rugby tackling them to the ground- if they are verbally abusing you, you are not.
The vague definitions do not help- 'damaging property' could mean smashing a window; it could also mean snapping a pencil in two. Legally, you could restrain a child for this, but ethically? It would be completely inappropriate. The legislation relies on teachers' judgements of what is reasonable, proportionate and necessary, and there is rarely any provision to train them to effectively make that kind of decision.
As a teacher, you have a duty of care to keep children safe, and act in loco parentis.
Whilst I understand that streakybacon's son was damaged by restraint (and this in itself would indicate to me that staff weren't properly trained), the duty of care extends to other children in the school who also need to be kept safe. I have had to restrain children with ASD to prevent them self injuring. Keeping everyone safe is key.
Sometimes touch can be a calming influence, but this must be professionally judged on each individual's history by the teacher.
Why on earth this is news is beyond me.