Mens rea is a necessary but not sufficient component of proving a criminal charge - the defendant intended to break the law. Actus reus is also required, which is actually doing the act.
US law doesn't "judge by intent". If you try to murder someone but you don't succeed, you don't get charged with murder.
Yes, I agree with you and I should have worded my comment better.
To keep with the murder example, intent is what separates 3v2, in most states. Yes, a crime was committed but was the intent to cause bodily harm vs actions causing bodily harm, without intent.
