First, that's called conspiracy.
No, it isn't. Conspiracy is when two or more people work together to attempt to commit a crime. It still requires
actus reus, generally, demonstrable acts which cannot be reasonably construed as anything other than an attempt to commit a crime, when the facts are understood together. E.g. buying fertilizer is not a crime. But buying ammonium nitrate fertilizer plus fuel, a detonator, gloves, and ski masks, and going to websites that provide information on bomb construction, and renting a van under a pseudonym using false ID, and being observed repeatedly investigating an area, and having drawn plans, and multiple people all clearing their schedule on the same day? Collectively those would add up to the
actus reus of conspiracy to commit terrorism. Even if the plan is never actually carried out, it was in fact a plan and demonstrable, concrete
actions were taken to make it happen:
actus reus.
You can look up the legal definition if you like. I don't know if you live in the US, but here at least, it is required at the federal level and most (if not all) states also require that at least one person in the agreement must make an overt act to bring the agreement about. If the agreement occurred but no one acted on it, it is not conspiracy. However,
everyone who was party to the agreement is guilty of conspiracy if even
one participant committed a single overt act toward that goal.
It takes more than one person, but they can be imprisoned for just wanting to do the crime.
No, they cannot. Because if I tell you that I'd like to murder Mr. Boddy, and you tell me "yeah, Mr. Boddy's a real jerk, let's off him", and then neither of us actually does anything, that's not conspiracy to commit murder. It's not even conspiracy to attempt murder, because no attempt was made. Even if both of us were 100% sincere in our stated desire to kill Mr. Boddy, we did nothing to actually bring that desire about. Whether or not you could establish
mens rea, there IS no
actus reus--and thus no crime.
Believe it or not, there's even a term for a related thing, the "impossibility defense", whether factual or legal. TL;DR: factual impossibility is when the alleged crime literally could not have been done, e.g. if I shoot a person with intent to kill them....and they are
already dead when I do that...then I didn't commit murder. (I could, however, be charged with
attempted murder, since that's a different crime with a lower
actus reus standard.) Legal impossibility is where the action being considered isn't even illegal in the first place, e.g. if I attempt to print bootleg copies of the first Nancy Drew mystery,
The Secret of the Old Clock, that's not a crime even if I was trying to commit intellectual property theft, because that book is now in the public domain--it's
not illegal to print my own handmade copies of that novel, regardless of whether I knew that.
Second, mens rea is there BECAUSE intent is the most important thing. Without the intent, there's no crime for that act.
Sure there is. In the US, 22 states have strict liability (=no
mens rea requirement) for
statutory rape (warning, SA). Further, traffic violations and other similar acts, some of which are still outright proper crimes, do not require any
mens rea component at all. Other countries such as Australia and Canada also have a small number of criminal offenses where strict liability applies. As an example, Australian air safety laws regarding the use of unmanned aircraft (read: drones) are often strict liability: all you have to demonstrate is that the act occurred, you don't need to demonstrate any
mens rea whatsoever.
So: no. The
mens rea is not the most important thing. In rare cases, it isn't relevant at all. In most cases, it is co-equally important with having actually done something worthy of guilt. Where there is no
actus reus, no deed of any kind commmitted, there can be no crime. Thankfully, we have not reached the point of having thoughtcrime yet.
If the action can happen with or without intent, but is only a crime if the intent is there, intent is the more important of those two components. It and it alone decides whether it's a crime or not. I also never claimed intent was the only part. Only that it was the most important.
But, as I have shown, it is
not the most important part. It is at best co-equal in importance with, y'know, the crime having actually been committed in the first place.
"The crime did not actually happen" is the strongest defense in the world if it is true. For example, in the Sherlock Holmes story
The Adventure of the Norwood Builder, (spoilers for those who are unfamiliar)
the alleged "victim" is actually alive and well. He either killed, or exploited the death of, a homeless man to fake his own death, in order to get revenge on the son of a woman who spurned him, and to evade his creditors. Holmes is able to draw him out of his hidey-hole by pretending that the house is on fire, forcing the man to escape. That this "victim" is, in fact, entirely alive would be a slam-dunk defense against the charge of murder. Hence: the guilty
act is just as important as the guilty
mind. No actual act? No crime. No guilty mind? No crime. They are individually necessary and jointly sufficient, in logic terms.
You aren't understanding the context of that comment. It was about whether the act was evil and therefore deserving of punishment, not whether they are prosecuted or get away with it.
How was I supposed to interpret the phrase "no one gets off the hook"? The meaning of the phrase "get off the hook [for]" something, means getting away with it without being punished.