Abstract
‘When is it appropriate for society to intervene paternalistically in a decision or decisions that individuals make as to their sexual relations?’ With these words, Sir Brian Leveson opened the judgement of the Court of Appeal in IM v LM1 and declared the key issue in the case. The Court of Appeal was provided with an opportunity to resolve a series of apparently conflicting decisions concerning the capacity to consent to sex. IM v LM will now be regarded as the leading authority on the question until the Supreme Court rules on it. The discussion in the case throws up some interesting issues on the nature of mental capacity and the definition of capacity within the Mental Capacity Act 2005.