A brief summary:
For some reason, the law makes a distinction between laws as follows:
Malum in se–meaning that the thing is bad in and of itself. Murder for example, is not bad because my state has enacted a law against it. It is immoral and wrong in and of itself in any decent society and is inherently wrong.
Malum Prohibitum–meaning that the thing is bad because the law says it is bad. Wikipedia gives the example of how the U.S. mandates that a driver must drive on the right side of the road. There is nothing inherently indecent or immoral about driving on the left side of the road as is done in the UK, but it is a regulatory custom to promote safety on the roadways.
I have problems with this distinction, especially as my state has the concept of desuetude in which it comes into play: https://en.wikipedia.org/wiki/Desuetude
First, isn’t the purpose of a regulatory law to promote public safety? If I say, fuck it, I am now driving on the left side of the road, endangering children and the public, am I not now doing something inherently wrong?
Second, the distinction seems to smack of religion and natural law. Although I have no problem with this, I would assume many (especially posters here) would. But regardless of that, we still have the issue of says who? For example are adultery and bigamy malum in se? On one hand, they are not regulatory constructs: these prohibitions and the inherent wrong contained in them have been around since the Code of Hammurabi. But then again so was homosexual sodomy, so ancient proscriptions cannot be the test.
What makes something inherently wrong? Whose moral code do we go by? Jerry Falwell, Larry Flynt or some hypothetical reasonable person? Is this reasonable person allowed to consult the Bible in his deliberation?
Finally, if religion cannot be a factor, then we must acknowledge that all laws, including those against murder, are just human constructs and eliminate the distinction. If religion can be a factor, then the courts will have to decide that this particular religion or this particular sect has the right idea about what is intrinsically wrong, and that this other religion who is more tolerant of the idea has the wrong view of it. That cannot be done in U.S. courts.
I think the whole doctrine needs to be abolished as inherently subjective as the distinctions are ones that a judge can objectively apply.