The Fifth and Fourteenth Amendments make it absolutely clear that the states CANNOT make ANY LAWS that deprive a person of life without due process.
Do you believe that an individual state should be allowed to pass a law legalizing murder?
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For the record, I do not. There are some crimes that deserve and even require a federal interest.
Do you believe that an individual state should be allowed to pass a law legalizing murder?
These amendments bar the federal government from doing so. Remember, the Constitution (as it was originally written) places limitations on the federal government as a treaty amongst the states, and the federal government only. It places no limitations on the states individually (pre Civil War as our country was founded). That is why every state has its own constitution spelling out the limitations by the people on their state's individual powers.
Do I believe that an individual state should be allowed to pass a law legalizing murder? No. But it is a state issue. Take the death penalty: a large number of people think it's state sponsored murder. However, as our founders created the Constitution, it's left up to the state and its populace to decide this. That's also why slavery was accepted for so long after the founding of our country; it was a state issue and up to the moral intellect of its people to decide the issue within the means of their own constitution.
With that said, if a state were acting tyrannical, the people would either move to a freer state or rise up and take over its government either by force or by election, but it would still be within the state. The way the founders created our confederacy, it makes states cater to the will of its own citizens without affecting the citizenry of its neighboring states; it creates competition amongst the states to attract the greatest and brightest of citizens, yet allows them to fail (as Michigan has done) and drive the ingenuity away.