re: No prison time for woman convicted in cannabis-induced killing

quote:

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Under California criminal law, people are responsible for their actions when impaired by alcohol or drugs unless their intoxication was involuntary.

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I'm not understanding the ruling here with regard to the above statement. It sounds like she should be help reaponsible. The statement is thrown in there like it's an explanation as to why on this ruling, but to me it seems contradictory. Am I missing something?