Not a big fan of the concept of charging people with unpublished (or obscurely published) common law crimes. I feel this is tantamount to "secret laws" and the public is not on fair notice as to what constitutes criminal conduct.
The Model Penal Code addresses an ignorance defense to a criminal charge in 2.04(3)(a):
Of course the MPC is not law - but it "has played an important role in standardizing the codified penal laws of the United States"
[SUP]1[/SUP] and I feel is a good reference point for topics like this.
I
believe that under the due process provisions of the 5th and 14th amendments no criminal penalty can be imposed without fair notice that the conduct is forbidden. Though I couldn't say where I learned it, that concept of requisite fair notice of prohibited conduct for crimes is something I have always understood to be fundamental to our system of law.
I'm not an attorney -- nowhere close -- but (as most of us have) I've put more effort into understanding the law than the average person. I have a bookshelf full of expensive books from WestLaw and LexisNexis. In short, I've put more effort into understanding my legal responsibilities than the law could ever expect a person to do. And despite that, I'll be darned if I can find any reference materials that would allow me to familiarize myself with any common law crimes in my state (or any other for that matter). I can find the statute that declares the common law to be in force here (in Florida) to the extent that it is "not inconsistent with the Constitution and laws of the United States and the acts of the Legislature of this state", but not much beyond that. There's plenty of publications available relating to common law application in matters of equity/laches -- and I think that's what most people think of when they think of common law -- equitable (civil) law, not crimes.
Unlike the readily available statutes of any state, details of common law crimes appear to be generally unavailable. I'm sure I'm missing something here. There's no way the public can be expected to know all of the crimes ever invented by any British court (or king) for all the centuries of cases and controversies up to July 4, 1776 (the cutoff for applicability of British common law here).
If there is a compendium of common law crimes, please do share the title. My bookshelf apparently has a hole in it that I never knew was there.