A MAN IN THE US IS apparently prepared to argue that caffeine pushed him into a mentally unstable state during which he killed his wife.

The New York Times reports that the Woody Will Smith, 33, from Kentucky, is due to face trial today. Smith is charged with murdering his wife Amanda Hornsy-Smith, 28, in May 2009 by strangulation.

His defence team has already filed papers showing it intends to argue that Smith consumed excessive caffeine from energy drinks and diet pills in the days before the killing, rendering him temporarily insane.

He says he remembers taking his children to school that morning, but little else of that day.

A mental disorder diagnosis manual published by the American Psychiatric Association says that 300mg of caffeine – about three cups of coffee – is technically an overdose.

The NYT writes that in 2009, a man was cleared of injuring two people after hitting them with his car by  claiming caffeine intoxication. A medical study of the case resulted in the diagnosis of a rare form of bi-polar disorder triggered by caffeine.

However, a prosecution witness could testify that there was no evidence of the caffeine ingestion claimed by Smith before the Kentucky murder. Smith could face life imprisonment if convicted.