R v O’Connor – Case Summary

R v O’Connor

Court of Appeal

Citations: [1991] Crim LR 135.


The defendant got into a drunken argument with the victim in a pub. He headbutted the victim three times, causing a brain haemorrhage which killed the victim.

At trial, the defendant contended that he believed at the time that he was acting in self-defence. The judge directed the jury that drunken intention is still intention. He made no direction in relation to the relevance of alcohol to self-defence. The defendant was convicted of murder. He appealed on the basis that the judge had misdirected the jury.

  1. Had the judge correctly directed the jury on the relevance of drunkenness to mens rea and self-defence?

The Court of Appeal quashed the conviction and substituted a conviction for manslaughter. The judge was correct not to direct the jury on the relevance of drink to self-defence. This was because defendants are not entitled to rely on drunken mistakes to establish a defence.

However, the judge had failed to direct the jury that intoxication may be relevant to whether the defendant formed the specific intention to cause grievous bodily harm. The conviction was therefore unsafe.

This Case is Authority For…

If the defendant forms a mistaken belief due to voluntary intoxication, this should not be taken into account by the jury.

Voluntary intoxication can be relevant to whether the defendant has the mens rea for a crime of specific intent. Murder is a crime of specific intent, because the defendant must intend to bring about a specific outcome (death or GBH), not merely to do a particular act.


The court noted that juries do not usually need to be directed on the issue of oblique intent save in rare cases. This is because causing the defendant normally desires what he intends.