Final answer:
The actus reus of section 18 GBH is intentionally causing harm. It is a serious form of non-fatal assault that requires the specific intent to cause grievous bodily harm, differentiating it from offenses that involve recklessness or negligence.
Step-by-step explanation:
The actus reus of section 18 GBH (grievous bodily harm) under UK law is b) Intentionally causing harm. This section, often referred to as wounding with intent, is the most serious form of non-fatal assault contrary to the Offences Against the Person Act 1861. Unlike other forms of assault which may involve recklessness, Section 18 requires a specific intent to cause grievous bodily harm. This differentiates it from Section 20 offenses, where the accused may have foreseen the risk of harm but did not specifically intend to cause it.
For a conviction under Section 18, the prosecution must prove that the defendant intended to cause serious injury, making it a more challenging offense to establish compared to negligent or reckless conduct. Notably, the injury inflicted must be severe; mere superficial wounds do not suffice to meet the legal threshold of 'grievous'.