Murder, also known as homicide, is defined as the unlawful killing of another individual. In order to be found guilty of murder, the prosecution must prove that the defendant acted with a required mental state. In first-degree murder, for example, a prosecutor must prove that the defendant premeditated the act and intentionally killed the victim.
Many defenses to homicide are formulated around the lack of the required mental state to commit the violent crime. The defenses a criminal defense attorney uses depends on the specific facts of the case in question.
The following are the most common types of defense strategies used in murder cases:
- Mistaken identity – In many murder cases, defendants argue that the prosecution charged the wrong person with the crime. Those who use the defense of mistaken identity often establishes an alibi if possible, which he or she attempts to support with evidence of being at another place at the time of the homicide. Furthermore, this defense can include challenges to forensic evidence and witness identification.
- Self-Defense – The defendant must demonstrate that the killing results from a reasonable use of force to resist a reasonable fear of death or physical injury. He or she cannot have instigated the situation, and the amount of force used in self-defense needs to be proportional to the threat perceived.
- Accident – Killings committed by mistake or accident in the course of lawful activities are not considered acts of murder. However, such killings may lead to manslaughter charges.
- Exercise of duty – Killings by police officers qualify as justified homicides if an officer kills another person in the exercise of duty and without an unlawful intent.
- Insanity – In regards to murder cases, insanity is defined as cognitively being unable to appreciate the quality of the act being committed, or unable to recognize that the act is wrong.