Let’s take the worst case scenario and assume that somehow pot was the direct cause of the child’s death. That would be tragic, of course, but in no way would it be sufficient data on which to justify the continued criminalization of marijuana. The argument in favor of legalization does not require marijuana to be absolutely harmless. Even if some proponents go so far as to claim that it is, then, it’s just an unnecessary premise (which means it can be discarded without any harm to the argument).
The main arguments in favor of marijuana legalization rest on parity. It’s classification as a Schedule I drug makes no sense from a scientific standpoint, and it’s dangers are minimal relative to other drugs that are already legal. Furthermore, the continued “war” against marijuana costs around $50 billion per year—not including the costs of incarcerating people, which the US now does at a higher rate than any other country in the world—all while doing nothing to decrease use of the drug and strengthening drug cartels.
In short, there is no scientific of legal basis for the continued criminalization of marijuana, and failing to legalize it does more harm than good. The death of a child is always sad, but it’s not worth manipulating national drug policy over it. Because even if we assume that marijuana was involved, that only proves that criminalization doesn’t change anything (since the drug is currently illegal).