What is the heat of passion?
The heat of passion is a criminal law concept that describes a mental state of uncontrollable rage which leads to an uncontrollable act of violence such as assault or murder. It is an anger or passion that is suddenly experienced by the defendant after he has been immediately and reasonably provoked. Reasonable provocation is decided by the members of the jury.
In other words, a defendant commits an act of violence, that fact is not questioned or denied by the defendant. He admits that he committed the violent act but argues that the only reason he did so was because he was suddenly and immediately provoked by some outrageous act of another. This is a defense to say a murder charge when provocation existed at the time of the felonious assault. Note that if any time whatsoever elapses between the provocation and the commission of the violent act, this defense is void.
If the defendant has any "cooling off" time, which can amount to even a few seconds, to fully consider the ramifications and or to deliberate about the matter in his mind, and or to have any time to premeditate about the act he is about to commit, if he is laying in wait for the victim, then he is guilty of assault, murder if applicable.