Glad this thread came along. Somehow, I had a fusion of knowledge between mistake of fact as a means of negating mens rea, vs factual impossibility being no defense. I was wondering how that could be true. Then I remembered that last one is specifically about criminal attempts. So possessing baking soda thinking it is cocaine would make one guilty of attempted possession, while possessing cocaine with a genuine belief that it really was baking soda, with it having never crossed your mind that it might be anything other than baking soda, might make one not guilty of possession, but only if the level of culpability required is set at something other than negligence (and even then you’d have a case if you could convince a jury that a reasonable person would not have perceived it as cocaine) or strict liability (in which case you’re screwed).
My understanding is that the government doesn’t need more information to tie that guy to a particular murder, it only needs evidence that there was a murder. If John Smith’s body was found, and a guy walks in and confesses, that’s admissible. If I walk in and say I killed a guy in the woods last week, I couldn’t be convicted because there’s no body, no missing guy, no bloody glove.
Can the government arrest (minus any real evidence) on a tip or confession and hold someone until further evidence does come in?
If there is probable cause. The Corpus Delicti rule doesn’t apply yet, but the principle might come into play. The absence of evidence might make it harder (but by no means impossible) to claim the police had a reasonable basis to believe the suspect committed a crime.
A confession is real evidence.
If police arrest the person, then they will need to be indicted (this often, but not always, precedes arrest) or, depending on jurisdiction and what the crime is, may be charged by information and then have a pretrial probable cause hearing. In general, neither of those processes require the corpus delicti rule to be satisfied. A confession alone is evidence. A vague and uncorroborated confession, though, might be rejected by a grand jury if they just don’t believe it.
Different jurisdictions enforce the corpus delicti rule differently at trial. For some jurisdictions, it is part of the prosecution’s burden of proof. In others, it is more a rule of evidence that must be satisfied for a defendant’s confession to be admissible.