Here are the key points about R v Kingston:
1. Kingston broke into a house and sexually assaulted two young girls while heavily intoxicated on alcohol.
2. Kingston claimed that due to his intoxicated state, his inhibitions were lowered and he gave in to impulses that he would normally have resisted when sober. Specifically, the judge said his intoxication lowered his resistance to "sexual impulses towards young girls".
So in summary, Kingston argued that while the intoxication did not remove his mental capacity entirely, it lowered his ability to resist impulses/urges that he could normally control when sober. The court accepted this could provide a defence to the specific intent crimes in his case