The initial aggressor is the person who first attacks or threatens to use physical force first.  The initial aggressor does not have to be the one who caused the first contact.

A person can use deadly physical force when they reasonably believe it necessary to defend themselves or others from the use or imminent use of deadly physical force on themselves or others.  Deadly physical force means physical force which can cause death or serious physical [...]

Serious physical injury means impairment of a person’s physical condition which creates a substantial risk of death, or which causes death or serious and protracted disfigurement, protracted impairment of health or protracted loss or impairment of the function of any bodily organ.

In New York, you have the obligation to retreat and not use deadly physical force if you can do so completely and safely.  However, there are exceptions to this rule including you do not need to retreat if you are in your own home and [...]

The insanity or Mental Disease or Defect defense is raised when a person charged with a crime lacked criminal responsibility at the time of the crime because they lacked substantial capacity to know or appreciate either: The nature or consequences of the conduct; or That [...]

If you are found not guilty by reason of mental disease or defect, your case is not over.  Instead, a new set of proceedings will be held to determine your current mental health condition, whether you are a danger to yourself or the community, and [...]

Intoxication is not a defense to a crime.  However, evidence of intoxication by drugs or alcohol can potentially eliminate an element of a charged crime.  In raising this issue, you must show that you could not form the mental state required to commit the crime.  [...]

Extreme Emotional Disturbance (EED) is a New York-specific defense in Murder cases only. To be clear if you are found to have committed a murder under an EED, you would be found not guilty of Murder, but guilty of Manslaughter. EED is a very different [...]