General Provisions
An act done in good faith for the benefit of a child under 12 or a person of unsound mind, by or with their guardian's consent, isn't an offence for resulting harm - except for intentional/likely killing, non-curative acts known likely to cause death, non-curative grievous hurt, or abetting an offence this exception wouldn't otherwise cover.
This lets parents/guardians consent to medical treatment on behalf of children or people of unsound mind who cannot consent for themselves - but with important safety limits excluding anything intentionally or foreseeably fatal that isn't genuinely for curing a serious condition.
A parent consenting to a risky but medically necessary surgery for their child is protected under this section, since it's genuinely for the child's medical benefit - but this protection wouldn't extend to consenting to something intentionally harmful with no genuine medical purpose.