Section 3.4: Legal Defenses

For a defendant to be found guilty of a crime in a criminal court, the prosecutor must prove all the elements of the crime beyond a reasonable doubt. However, in some cases, there are additional factors to consider. The prosecutor must also demonstrate that the defendant committed the actus reus (the physical act) and mens rea (the intent or knowledge) without any valid justification or excuse.

In the legal system, justifications and excuses are types of defenses that a defendant can raise in response to criminal charges. If successful, these defenses can lessen or eliminate the defendant’s culpability.

A justification is a valid reason for committing an act that is typically considered a crime. For example, it is generally against the law to shoot someone. However, if the person being shot was attempting to harm the shooter with a knife, the shooter may be able to raise the defense of self-defense. Justifications acknowledge that the act was legally wrong but the right thing to do given the circumstances.

An excuse is different from a justification. It is a reason that explains why the defendant committed the act but does not necessarily make the act right. Excuses acknowledge that the act was wrong but argue that the defendant should not be held fully responsible for their actions. Examples of excuses include insanity, duress, or being under the influence of drugs or alcohol at the time of the crime.

The Insanity Defense

Insanity is a legal term used in the court of law, not in medicine or psychology. It is essential to understand that simply having a mental illness or defect cannot excuse one’s guilt. For example, although Jeffrey Dahmer committed heinous crimes, he was legally determined to be sane. To use insanity as a legal defense, the defendant must prove that they could not understand that the act was wrong or the nature of the act itself. Some jurisdictions allow for a plea of not guilty by reason of insanity.

The concept of the insanity defense is based on the ideas of mens rea and culpability. As a society, we generally only want to punish individuals who are aware that their actions are wrong. Punishing someone for an accidental act or punishing young children for adult crimes is usually considered morally wrong. If a person is so mentally ill that they do not understand that their actions are wrong, then it would be unjust to punish them.

Different courts have developed various tests to determine whether a criminal defendant is legally insane. One of the oldest and most enduring tests is the M’Naghten Rule, which is based on the defendant’s ability to distinguish right from wrong. Another test is the Irresistible Impulse Test, which considers whether the defendant could control their actions due to mental illness. Today, most courts use the substantial capacity test developed within the Model Penal Code, which includes both the awareness of wrongdoing standard of M’Naghten and the involuntary compulsion standard of the irresistible impulse test.

Contrary to popular belief, the insanity defense is rarely used and even less successful. Most individuals who use this defense spend more time in mental institutions than they would have spent in prison had they been convicted. Therefore, the insanity defense should not be considered a “get out of jail free card.”

Entrapment

Entrapment is a defense that can be used to remove blame from a person who has committed a criminal act, but only if they were convinced to do so by law enforcement. This means that if the police lure someone into committing a crime, that person can claim entrapment as a defense. To successfully claim entrapment, two related elements must be present: government inducement of the crime and the defendant’s lack of predisposition to engage in criminal conduct.

Mere solicitation, or asking someone to commit a crime, is insufficient to establish inducement. The government must go beyond solicitation and use persuasion or mild coercion to induce the defendant to commit the crime. The defendant must not have had a prior predisposition to commit the crime, and the government must have played an active role in encouraging or facilitating the commission of the crime.

Entrapment is not a defense that can be used in all situations. It only applies when the government has induced an otherwise law-abiding citizen to commit a crime. For example, suppose a person with no prior history of drug use is approached by an undercover officer who repeatedly pressures them to buy drugs, and the person eventually gives in and buys drugs. In that case, they may be able to claim entrapment.

Self-defense

In political theory, the concept of the social contract is a fundamental idea that explains how people agree to give up certain individual rights in exchange for the protection and security provided by the government. The social contract theory suggests that individuals voluntarily agree to form a society and establish a government to maintain order, protect their rights, and ensure their safety. One of the primary roles of government in the social contract is to provide security and maintain law and order, which includes the right to use force.

The power to use force is critical to maintaining law and order in society. However, this power is typically entrusted to law enforcement officers trained to use it judiciously and follow the law. Therefore, in most cases, when force is necessary to end a confrontation or prevent harm, people are advised to call the police. This is because law enforcement officers are authorized to use force in a manner that is consistent with the law and that upholds the principles of justice and fairness.

However, there may be rare instances when the police are unavailable in an emergency. In these situations, ordinary citizens may be required to use force to protect themselves or others from harm. For example, if someone is being attacked or threatened, they may need to use force to defend themselves or others. In such cases, the use of force may be permissible and legally justifiable.

The legality of using force in self-defense is based on the principle of reasonableness. In other words, the use of force must be proportionate to the threat and should only be used as a last resort. When defending oneself or others, the amount of force used should be the minimum necessary to repel the attack. This means that excessive force should be avoided. The reasonableness of the use of force will always depend on the circumstances of the individual situation.

In self-defense, it is also essential to consider the immediacy of the threat. In other words, the threat must be an imminent danger, meaning there must be a present and immediate risk of harm. The use of force cannot be preemptive or retaliatory, meaning that it cannot be used to prevent a hypothetical or future threat.

In general, using deadly force is only justifiable when it is necessary to prevent the loss of life. This means that, in most cases, non-deadly force should be used to prevent theft or other non-life-threatening crimes. However, the specific laws regarding the use of force may vary depending on the jurisdiction.

Intoxication

In criminal law, mens rea refers to a person’s mental state or intention when committing a crime. It is a fundamental element of most criminal offenses and refers to the intention or knowledge that a person has when engaging in an illegal act. In general, mens rea refers to the defendant’s mental state at the time of the crime and is a critical element in determining criminal liability.

Intoxication is a state of being under the influence of alcohol or drugs. It is a factor that can affect a person’s judgment, decision-making, and ability to control their behavior. While it is generally understood that intoxication can impair a person’s ability to form mens rea, it is not considered a valid defense in most cases.

However, some jurisdictions may allow voluntary intoxication as a factor that lessens criminal culpability. The defendant may argue that their intoxication reduced their ability to form the necessary criminal intent or mens rea. As a result, they should not be held fully responsible for their actions. This defense is often used in cases of murder or other serious crimes.

Involuntary intoxication, on the other hand, is a different matter. It occurs when a person is intoxicated without their knowledge or consent. This can happen when someone is drugged by another person, given a drug that has unforeseen effects or has taken medication as prescribed by a doctor without realizing that it will impair their judgment.

Involuntary intoxication is typically considered a valid defense because the defendant did not have control over their state of mind at the time of the crime. The defense argues that the defendant lacked the necessary mens rea because they were not aware of the effects of the drug. However, the availability of this defense may vary depending on the jurisdiction, and the burden of proof is on the defendant to show that they were involuntarily intoxicated at the time of the crime.

Mistake

The legal system recognizes that people are not perfect and can make mistakes. A mistake defense can sometimes be used when it comes to criminal charges. Two types of mistakes can be used as a defense in a criminal case: mistakes of fact and law.

Mistakes of fact occur when a person misunderstands or is mistaken about the details of a situation. For example, if someone takes something they believe to be abandoned property, but it turns out to belong to someone else, they may be able to use a mistake of fact defense. In such a case, the person genuinely believed they were not committing a crime, and their mistake may be considered a defense.

Mistakes of law, on the other hand, occur when a person misunderstands or is mistaken about the law. For instance, if someone is unaware that driving under the influence of alcohol is a criminal offense, they may not be able to use a mistake of law defense. The reason for this is that there is a presumption in American law that everyone knows the criminal law. This means that if someone commits a crime, they are presumed to have known their actions were illegal.

This presumption is essential because if it were not in place, it would be difficult to prosecute crimes. Without the presumption that people know the law, anyone could commit a crime and then claim that they did not think it was illegal. This would undermine the entire legal system and make it very difficult to enforce laws.

Necessity

The necessity defense is a legal defense that allows a person to commit a criminal act if it was necessary to prevent greater harm. This defense is based on the idea that sometimes we have to choose between two evils and that it is better to choose the lesser of the two. For example, if a person breaks into a store to steal food to feed their family, they may be able to use the necessity defense if they can show that they had no other way to obtain the food.

The necessity defense is also known as the lesser of two evils defense because it requires that the harm the person is trying to prevent be greater than the harm caused by the criminal act. In other words, the person must be able to show that they acted to prevent greater harm and that the harm they caused was the lesser of the two.

However, there are some limitations to the necessity defense. In most jurisdictions, the defense will not be available if the person created the danger they were avoiding. For example, if a person starts a fire that constitutes the greater harm, they cannot use the necessary defense because they created the danger they were trying to avoid.

It is important to note that the necessity defense is not available in all cases, and it is up to the judge or jury to decide whether the defense applies in a particular case. The defendant must be able to provide evidence that their actions were necessary to prevent a more significant harm and that they had no other reasonable options available. If the defense is successful, it may mitigate or eliminate the criminal charges against the defendant.

Duress

Duress, also known as coercion, is a legal defense that allows a person to avoid criminal liability if they commit a crime under the threat of harm or injury. This means that the person did the criminal act because they were forced to do so by another person who threatened to harm them or someone else if they did not comply with their demands. While the person commits the actus reus of the offense, the mens rea element, the criminal intent, was that of the person who coerced them to commit the crime.

The duress defense is based on the idea that the person had no other reasonable option but to commit the crime and that they were not acting with criminal intent. The effect of a successful duress defense is a matter of state law and may differ in different jurisdictions. In some states, the defense may result in a complete acquittal, while in others, it may only result in a reduced sentence.

To use the duress defense, the defendant must be able to show that they had no part in becoming involved in the situation. This means that the person did not voluntarily put themselves in a situation where they would be threatened or coerced. For example, suppose a person agrees to participate in an illegal activity and is later threatened to continue participating. In that case, they may be unable to use the duress defense because they voluntarily put themselves in that situation.

Summary

The legal system requires prosecutors to prove all elements of a crime beyond a reasonable doubt, including the defendant’s physical act (actus reus) and intent or knowledge (mens rea) without a valid justification or excuse. Justifications and excuses are types of defenses that can lessen or eliminate the defendant’s culpability. Justifications are reasons for committing an act that is typically considered a crime, while excuses explain why the defendant committed the act but do not necessarily make it right. Examples of excuses include insanity, duress, or being under the influence of drugs or alcohol at the time of the crime.

Mistakes of fact and mistakes of law are two types of mistakes that can potentially be used as defenses in a criminal case. The insanity defense is based on the idea of mens rea and culpability, where a defendant must prove that they did not have the capacity to understand that the act was wrong or the nature of the act itself. Entrapment is a defense that can be used when a person commits a crime because they were convinced to do so by law enforcement. Self-defense is the legal use of force to protect oneself or others from harm, while intoxication is a state of being under the influence of alcohol or drugs. Finally, the necessity defense allows a person to commit an illegal act if it was necessary to prevent more significant harm, and the duress defense allows a person to avoid criminal liability if they committed a crime under the threat of harm or injury.

References

• M’Naghten’s Case, 10 Cl. & Fin. 200 (1843).
• Model Penal Code § 2.08 (1962).
• Parsons v. State, 481 P.2d 287 (Alaska 1971).
• United States v. Russell, 411 U.S. 423 (1973).
• United States v. Velasquez, 885 F.2d 1076 (3d Cir. 1989).

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Last Updated:  07/13/2023

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