It depends a lot on body weight, body mass, what else has been consumed and how quickly the alcohol was consumed. You can feed the same person the same amount of alcohol but if it's over 4 hours rather than 1, the result will be different.
The upshot of it is, drinking 3 pints over 3 hours, may make you unstable a lot quicker than if you drank 3 pints over 8 hours.