Back in the day in my country, you could apparently get milder punishment if you were driving while drunk, because it's harder to steer properly then. From https://commons.wikimedia.org/wiki/File%3ABilkrock_i_%C3%A5s...:

> In 1928, a serious accident involving considerable property damage occurred on the main road [...] At the subsequent trial in Klippan, it was said that the Örkelljunga resident, who had caused the accident, received a more lenient sentence because he had been drinking spirits and therefore had difficulty steering.

Different times :)

It is a form of temporary insanity, I suppose (though self-induced).