Alcohol tends to lower people's inhibitions and affect their ability to reason – which is why alcohol is heavily associated with everything from bar fights and thefts to other poor choices.
Can intoxication ever be used as part of your defense if you're charged with a crime? Like most things in the law, the answer depends on the situation.
Was your intoxication voluntary or involuntary?
Generally speaking, you're going to have a much easier time raising involuntary (as opposed to voluntary) intoxication as a defense. For example, if you had no idea that you were drinking from a spiked bowl of punch, that can generally be used as a defense for your subsequent actions – even if they were illegal.
Voluntary intoxication, however, is a whole different situation. If you knew you were drinking, you cannot use your intoxication as a defense in certain crimes where “specific intent” is not required for culpability.
In plain language, what does that mean? Well, for example, you can't blame voluntary intoxication for your decision to drive home from the bar, no matter how unusual that kind of behavior may be for you.
You could, however, raise voluntary intoxication as a mitigating factor if you were drunk when you ended up in a fight where someone died, and you're now charged with murder. While it won't serve as an absolute defense that will negate the charges against you, it could help you get the charges reduced or get a lower sentence.
The idea of “diminished capacity” to form the specific intent to commit a crime has a long history in California, and the use of that defense has evolved over time. Make sure that you fully understand your options if you want to use intoxication as part of your defense moving forward.