Defenses to Murder Charges in California

Building a Strong Defense in High‑Stakes Homicide Cases

Being charged with murder is one of the most serious situations a person can face. Police assign their most experienced detectives to homicide investigations, and prosecutors devote significant resources to secure convictions. Because the penalties can include life in prison, life without the possibility of parole (LWOP) or, in rare cases, capital punishment, anyone accused of homicide must mount a comprehensive defense immediately.

Radford & Rome, LLP is a Los Angeles‑based law firm that defends clients in Los Angeles, Orange, San Bernardino, Riverside, Ventura and San Diego counties. As former prosecutors and experienced criminal defense attorneys, we understand how prosecutors build murder cases and the strategies that work to defeat or reduce charges. Below we describe several defenses that can apply in murder and manslaughter cases along with the legal basis for each.

Self‑Defense or Defense of Others

California recognizes that a person may use deadly force to defend themselves or others from an imminent threat. Penal Code § 197 lists circumstances under which a homicide is justified. The statute authorizes lethal force when a person reasonably believes they or someone else is about to be killed or suffer great bodily injury, and the force used is proportionate to the threat. CALCRIM 505 instructs jurors to consider whether the defendant honestly and reasonably feared imminent harm and whether the response was necessary and proportional.

Key points for self‑defense:

• Imminent danger: The defendant must have reasonably believed they or another person faced immediate death or great bodily harm.
  
• Proportionality: Deadly force is permitted only if the perceived threat also involved deadly force; the response cannot be excessive.
  
• No provocation: Typically the defender must not be the initial aggressor unless they attempted to withdraw and were pursued.
  

Example: An individual is assaulted by someone wielding a knife. If the person uses a firearm to stop the attack, believing that their life is in danger, the killing may be justifiable as self‑defense if a jury agrees the fear was reasonable and the force used was necessary.

Accident and Manslaughter – Lack of Intent

To convict someone of murder, prosecutors must prove malice aforethought — an intent to kill or reckless disregard for human life. If the death was an accident or resulted from negligence, the charge may be reduced or dismissed.

Excusable accident

Under CALCRIM 510, a homicide is excusable if the defendant caused the death while performing a lawful act with ordinary caution and without criminal negligence. The instruction emphasizes that when the killing is purely accidental and the defendant used reasonable care, they are not guilty of murder or manslaughter. For example, lightly pushing a friend as a joke only to have them trip, fall and suffer a fatal head injury may constitute an excusable accident if the shove was not intended to harm.

Manslaughter

If the killing was unintentional but involved some form of negligence or occurred during a sudden quarrel, prosecutors may pursue manslaughter charges instead of murder. California Penal Code § 192 describes two types relevant here:

• Voluntary manslaughter occurs when a person kills in the heat of passion or upon a sudden quarrel without premeditation. This defense is often raised when the evidence shows the defendant acted impulsively under intense emotional provocation.
  
• Involuntary manslaughter involves the unintentional killing of another person through either an unlawful act not amounting to a felony or through a lawful act performed without due caution. Involuntary manslaughter requires proof of criminal negligence; there is no intent to kill. The statutory penalty is 2, 3 or 4 years in county jail and fines.
  

Voluntary and involuntary manslaughter are less serious than murder because they lack malice. Demonstrating that a killing occurred during a fight under extreme provocation or as a result of negligence rather than intentional violence can substantially reduce potential penalties.

Diminished Capacity (Mental Impairment)

Although California abolished the broad “diminished capacity” defense, evidence of a mental disease or disorder is still admissible to negate specific intent or malice. Penal Code § 28 permits mental‑health evidence solely on the question of whether the defendant formed the intent or mental state required for the crime. The statute states that evidence of mental disease or defect is admissible to show whether the defendant actually harbored malice aforethought or deliberated. Penal Code § 29 adds that expert witnesses may describe the defendant’s mental illness but cannot opine on whether the defendant actually possessed the required intent; that determination is reserved for the jury.

CALCRIM 3428 instructs jurors that they may consider evidence of the defendant’s mental disorder when deciding whether the defendant acted with the intent or mental state required for the charged offense. This is sometimes called “diminished actuality” — it does not excuse the conduct but can reduce a murder charge to manslaughter if the defendant could not form malice or deliberation due to mental impairment.

Example: An individual with severe bipolar disorder experiences a manic episode and impulsively kills someone. If experts show the disorder prevented the person from understanding or controlling their actions, the jury may reject murder and instead convict on manslaughter.

Insanity Defense

In rare cases, a defendant may plead not guilty by reason of insanity. Under California law, a person is legally insane if, at the time of the offense, they either did not understand the nature and quality of their act or could not distinguish right from wrong. This standard derives from the M’Naghten rule. The defendant bears the burden of proving insanity by a preponderance of the evidence.

Two‑phase process

1. Guilt phase: The jury first determines whether the defendant committed the crime. Mental‑health evidence may be introduced to challenge intent (diminished actuality), but the question of insanity is reserved for the next phase.
   
2. Sanity phase: If the jury finds the defendant guilty, the trial moves to the sanity phase. The defense must prove the defendant was legally insane at the time of the offense. This usually involves extensive psychiatric testimony and evaluation of medical history, diagnoses, and evidence of delusions or psychosis.
   

If the jury returns a verdict of not guilty by reason of insanity, the defendant is not released. Instead, they are committed to a state psychiatric hospital for treatment, often for as long as they would have spent in prison if convicted. Release is possible only when experts and the court agree the person no longer poses a danger to society.

Challenges and considerations

• High burden of proof: The defendant must convince the jury that their mental illness prevented them from understanding the nature of the act or from knowing it was wrong. Simply having a mental illness is insufficient.
  
• Jury skepticism: Jurors may be skeptical of insanity pleas due to misconceptions about mental illness and concerns about public safety. Competing expert testimony can also create confusion.
  

Because of these challenges, the insanity defense is rarely used and even more rarely successful. However, for defendants suffering from severe mental illness, it can be lifesaving.

Mistaken Identity and Alibi

Eyewitness misidentification is a leading cause of wrongful convictions. An alibi or evidence that the defendant was elsewhere at the time of the crime can be a powerful defense. CALCRIM 3400 instructs that the prosecution must prove the defendant was present at the crime scene; the defendant has no burden to prove they were elsewhere. If jurors have a reasonable doubt about the defendant’s presence, they must acquit.

Examples of mistaken identity defenses:

• Alibi evidence: Phone records, video footage or testimony showing the defendant was in another location at the time of the crime.
  
• Challenging eyewitness testimony: Showing that witnesses had only fleeting glimpses, poor lighting, or cross‑racial identification issues.
  
• Forensic discrepancies: DNA or fingerprint evidence that does not match the defendant.
  

Why Experience Matters

Every murder case is unique. The viability of a particular defense depends on the facts, the quality of the evidence and the skill of counsel. Prosecutors often overcharge defendants with murder even when evidence suggests manslaughter or self‑defense. An experienced attorney can investigate the circumstances, consult mental‑health experts, challenge forensic evidence and present a compelling narrative to the jury.

At Radford & Rome, LLP, we have decades of experience handling homicide and violent‑crime cases across Southern California. As former prosecutors, we know how investigators build cases and where weaknesses may exist. We provide personal, strategic representation aimed at achieving dismissals, reduced charges or acquittals.

Contact Us Today

If you or a loved one faces murder or manslaughter charges, do not wait. Contact Radford & Rome, LLP for a confidential consultation. Our attorneys serve Los Angeles, Orange, San Bernardino, Riverside, Ventura, and San Diego counties. We will listen to your side of the story, explain your options and fight tirelessly to protect your freedom and future.