The law of the insanity defense is a rabbit hole that one can spend a lot of time in. Each state implements it differently. Hence, the idea that the Lindsay Clancy trial is going to create a national wave of women killing their kids and getting off is probably overblown because, as this article points out, the Massachusetts law is unique. The Massachusetts law is pro-defense but I don’t think you can put the enactment of these laws into the standard “liberal vs. conservative” box. States like New York, Washington and Wisconsin have some of the most “pro-prosecution” insanity laws on the books. Some “conservative” Southern states have the “guilty but mentally ill rule” which favors the defense. Its a patchwork.
True, Massachusetts law on this particular issue is an outlier, which I should of noted but forgot to. But I do believe it can create fertile ground for a plethora of insanity defenses on a host of things.