The one being discussed is "criminal intent". It's an admittedly fuzzy term, but clearly if you're murdering someone, you have criminal intent regardless of your knowledge of whether it is illegal.

Well... mostly clearly. Clearly enough in the murder case, but there's certainly fuzzy cases. Still, there are an awful lot of crimes on the book that when you lack criminal intent, it doesn't actually make sense to prosecute from either a "rehabilitation" or "punishment" point of view, such as the ones in the article. What did society gain by any useful metric in the orchid case? In fact it lost a lot for no good reason.