Mistake of Law: Requisite of Intent - Distinguishing Nuance

Question

Background: I am not a law student, I am a graduate student in mathematics who intermittently enjoys reading about law because I find it axiomatic, deductive and occasionally creative - similar to mathematics. You could say it is a hobby for me.

Context: I was reading about 'mistake of law' defense on a website (I do not know how credible or outdated this website may be). In short, here is what they had to say -

"Mistake of Law: A mistake involving the misunderstanding or incorrect application of law with regard to an act or transaction. The defense of mistake of law raises two issues. The first issue occurs where, because of a mistake of law, the defendant did not have the requisite intent to commit a crime. The second issue occurs where, because of a mistake of law, the defendant did not know that an act that he committed intentionally was criminal. It is important to understand the distinction between these two issues because, while mistake of law will usually be allowed as a valid defense in the former situation, it will generally not be allowed in the latter situation."

It had a quiz at the end so you could test yourself to see if you understood the subtle difference. I answered the first two questions correct, but only because there were similar examples in the article that set a precedent for how I answered. I have a few closely related questions regarding the two scenarios in the quiz, and the defense in general. I provide screenshots of the quiz below:

Analysis: From the highlighted definition / explanation of 'mistake of law' defense above, and the green highlighted explanations in the pictures - this website is implying that the distinction between a successful application of mistake of law defense and unsuccessful mistake of law defense entirely boils down to 'requisite intent' - although they do not give a clear definition of this. My interpretation of the arguments for defense in the scenarios is as follows:

Argument for Scenario 1:

1. Defendant comes into possession of lost property.
2. Defendant falsely believes that a law exists stating that if lost property is not claimed within two months finder gains ownership of lost property.
3. Defendant waits two months.
4. Because of the mistake, at this time defendant falsely believes lost property becomes defendants property.
5. As defined in the question larceny requires the intention of permanently depriving an owner of their property.
6. By (4) - at the time defendant made the transaction that would constitute permanently depriving plaintiff of ostensible property, defendant believed ownership was transferred to defendant.
7. Defendant did not have intent to commit larceny
8. By definition defendant is not guilty of larceny.

Argument for Scenario 2:

1. Defendant comes into possession of lost property.
2. Defendant believes "the law allows for someone to do whatever they want with lost property even if they know who the rightful owner is".
3. Defendant sells necklace - purposely and permanently depriving the owner of their property.
4. By definition, defendant has committed larceny.

Actual Questions:

1. In scenario 2, to say "the law allows for someone to do whatever they want with lost property even if they know who the rightful owner is" seems like a laymen way of saying the defendant believed that finders of lost property immediately acquired ownership. It also seems from the analysis that had this been the defendants statement - it would have been a 'successful' application of the defense. Is the wording of the defense the tipping point of what makes this an 'unsuccessful' application?
2. Both of these examples and scenarios are 'isolated' to help get a point across to a reader, that said - just because we have argued that defendant is not guilty of larceny in scenario 1, could the charge be adjusted to a crime that does not specifically require intent? Could a judge 'overrule' that defendants 'mistake' was 'unreasonable'? By the contrived example of scenario 1 it seems it would be a valid to defense to simply claim that every defendant thought a law existed that somehow removed their intent to commit the crime as defined, but surely this cannot be.
3. No longer specific to the examples above, do mistake of law defenses actually occur in modern legal situations?

Closing Remarks: Please note that I am new to this stack exchange community. I tried my best to keep my question on-topic as defined in the help page - but please feel free to offer advice regarding social norms of this community, e.g. feel free to tell me if my question is silly child's play and this community is for more serious questions. I also had a hard time choosing appropriate tags since 'legal defenses' is not a tag, please adjust as needed.

Answer 1

1. I don't think that's an accurate interpretation of the statement. The key difference between the two scenarios is the defendant's legal assessment of who owns the necklace. In the first he thinks he is the owner and can claim mistake of law; in the second, he he thinks someone else is the owner, so he cannot. To say he believes "the law allows for someone to do whatever they want with lost property even if they know who the rightful owner is" is very different from saying he thinks he's the owner. He doesn't think he's the legal owner, he just thinks he has legal rights that include some rights associated with ownership.

   So if the defendant's statement had actually been, "I thought I was the owner," that would have been a successful defense when the crime requires depriving the owner of the property. The defense was actually, "I thought I was allowed to deprive the owner of the property," which is an admission of guilt when the crime requires depriving the owner of the property.

2. There are a couple questions here:

   a. A different crime that did not require intent -- or even required a different kind of intent -- could still lead to a conviction. A legislature is free to define larceny differently, so it could say that anyone who recklessly or negligently deprives another of property is guilty. Or it could say that your state of mind doesn't matter and that depriving another of property is larceny regardless of intent.

   b. In most cases, the mistake of law defense requires that the defendant honestly believe in the mistake; unlike mistake of fact, it does not require that his belief also be reasonable. Either way, the question of reasonableness would probably be a question for a jury, so a judge wouldn't be able to reject it (except in a bench trial).

   c. Mistake of law is a potential defense to any crime that requires an intent to do something that requires an assessment of what the law is. So if it's illegal to intentionally have sex with a woman who is not your wife, and you mistakenly believed you were in a legal marriage, sex with your non-wife would not be a crime.

   It has potentially very broad implications, but keep in mind that in many cases, the mistake a defendant would have to claim would be pretty far out there. If it were illegal to intentionally let anyone under 21 years old into your bar, I guess you could argue that you only let a 20-year-old in because you thought the law started calculating at conception, but I doubt you'll convince a jury.

3. Mistake of law defenses still pop up pretty regularly. Here's one just yesterday from the Tenth Circuit. And this one is a Kansas case where a conviction for carrying a weapon while a felon was overturned because the court wouldn't allow a mistake-of-law defense. The Kansas case, though, uses the more modern definition of mistake of law, which also includes reasonable reliance on official statements from the government. In that case, the felon's parole officer had told him that it was OK to carry a pocketknife, but in reality, the law titled "Criminal possession of a firearm by a convicted felon" prohibited carrying knives, as well.