Self Defense

The legal term self defense refers to a type of affirmative defense used to explain one person’s use of force against another person. For example, self defense describes a situation wherein one person reasonably uses force to defend himself against an attack by another person on the subway. A person might use non-deadly force, or deadly force, to defend himself, depending on the situation. To explore this concept, consider the following self defense definition.

Definition of Self Defense


  1. The act of defending oneself, one’s family, or one’s property through the use of force.
  2. A plea of justification for the use of force, or for the killing of another person.


1645-1655       English common law

Self Defense Laws

Self defense laws in the U.S. dictate that a person is allowed to use force against another person if it “reasonably” appears necessary to do so. Situations that would call for the use of force involve those wherein a threat of “unlawful” and “immediate” violence has presented itself. In these cases, a person may be permitted to use either deadly or non-deadly force in order to protect himself or his family.

Self defense laws restrict the protections of such a defense for those who initiate the conflict. There are two ways a person can remain protected under self defense laws if he was the one to start the conflict. The first is if he chose to leave the fight and informed the aggressor of his surrender, and the aggressor pursued him anyway. The second is if the other person responded to the presentation of a conflict with excessive force.

What follows is an example of self defense that would be permitted as a defense for an aggressor:

Billy discovers that Jack has been physically abusive toward Billy’s sister, Emily. Billy goes to the local bar, where he knows Jack likes to hang out, and punches Jack in the face. Billy immediately regrets what he did and apologizes to Jack, but Jack does refuses to accept Billy’s apology. Instead, Jack pulls a gun on Billy.

Despite the fact that Billy had originally started the fight, Billy would be justified in using force against Jack to restrain him, or otherwise disarm him, due to the immediate threat that Jack is posing to Billy’s life. In this example, Jack clearly responded to the situation with excessive force.

Right of Self Defense

The right of self defense is the right for a person to use reasonable force to defend himself, his property, or the lives of others. If necessary, the use of deadly force can be permitted, depending on the circumstances. Once someone uses excessive force, which is more force than the situation truly calls for, then he gives up his right of self defense. In that case, he goes from being the person defending himself to the aggressor in the action. If a defendant exercises his right of self defense as a response to a threat of death or serious harm, then he is said to have a “perfect self defense” justification.

Reasonable Force

Reasonable force refers to the amount of force that is necessary for a person to defend himself or his property, without going overboard. It is especially important to prove whether or not the force a person used was reasonable in order to determine his level of liability for the crime. Hence why reasonable force is also referred to as “legal force.”  For instance, a father who gets into an argument with his son’s baseball coach, shoving him with his hands, has started the conflict. If the coach, in defending himself, picks up a baseball bat and slams it into the father’s head several times, it could not reasonably be considered self defense.

If a person can prove that he used reasonable force to defend himself, he may be able to avoid being prosecuted for a crime.

If a person uses more force than what would be considered necessary to protect himself from an aggressor, then this would be considered excessive or unreasonable force. Once excessive force has been proven, then the defendant’s self defense argument is considered forfeited. For instance, a defendant is justified in using force that is intended or likely to cause death or severe injury if someone violently enters his home, and he believes such force is necessary to prevent harm from coming to himself, or to another person in the home.

Reasonable Force and the Police

Because police officers deal with imminent threats on their lives every day, courts decide on a case-by-case basis whether or not an officer’s use of force was reasonable. Elements that are considered include the severity of the crime, whether the suspect did indeed pose a serious threat, whether the suspect had a weapon, and whether the suspect was resisting arrest or trying to run away. If an officer is found to have used unnecessary force, then he can be subject to serious punishments, such as being brought up on criminal charges, or being sued by the victim in civil court.

The amount of force that an officer is permitted to use is a hot topic that often leads to controversy. Police officers are permitted to use as much force as they “reasonably” believe is necessary at the time of the arrest in order to protect both themselves and the public. However, those belonging to ethnic or racial minority groups often oppose the level of force that officers choose to employ.

While officers are permitted to use deadly force to prevent a dangerous suspect from escaping – and potentially harming more people – they are required to give a warning whenever possible. Deadly force is considered unjustified when the suspect does not pose an immediate threat to the officer, nor to anyone else.

Duty to Retreat

In criminal law, there is a requirement known as the duty to retreat. The duty to retreat is the condition that a person who is being threatened should not “stand one’s ground” and use deadly force to defend himself. Instead, he should retreat from the situation and seek safety, if that is possible.

When the duty to retreat is used in conjunction with self defense as a legal defense, it is up to the defense to prove that the defendant was acting reasonably by avoiding conflict. The defense must also show that the defendant had done everything he reasonably could to retreat and, in doing so, showed that he had no intention to fight before being forced to use force in order to defend himself. Only a small percentage of states currently have duty to retreat laws.

There are certain situations, however, wherein the duty to retreat is not possible or reasonable, such as when a person is threatened in his own home, or at his place of business. Police officers, on the other hand, are not obligated to retreat when presented with imminent threats of danger while on the job. The fact that a person’s home or workplace are exempt from the duty to retreat is known as the “castle doctrine.”

Imperfect Self Defense

Imperfect self defense is a common law, which holds that a defendant can avoid punishment for using deadly force, so long as he can prove that he had an honest – if unreasonable – belief that his actions were necessary. The idea here is that, if a defendant possessed an unreasonable belief that it was necessary for him to use force to defend himself in a given situation, he could not have acted with malice. For the prosecution, malice is a particularly important element to prove when seeking a murder conviction.

In using an imperfect self defense, a defendant may be able to reduce his liability for his crime. For instance, in some jurisdictions, the successful usage of imperfect self defense can reduce a murder charge to manslaughter. However, most jurisdictions do not permit imperfect self defense to be used as a legitimate defense.

Self Defense Example in a Spousal Abuse Case

An example of self defense presents itself in a case involving spousal abuse. Betty Moran had repeatedly endured brutal beatings at the hand of her husband, Willie. According to Betty, Willie had a violent temperament, an extensive collection of firearms, and was always armed. On one occasion, Willie was holding her by her throat and hitting her with one of his guns.

On May 15, 1981, Betty and Willie had fought their final fight. According to Betty, Willie had asked her earlier that day to give him some money he thought she had saved. He threatened Betty that if she did not have the money ready for him by the time he awoke up from his nap, he would “blow [her] damn brains out.”

Betty did not actually have the money that Willie thought she did, and instead she called a friend to possibly loan her the money. When that did not work, and she realized there would be no way for her to get the money Willie requested, she walked into the camper where he was asleep, picked up his gun, and shot him.

Betty was arrested and charged with murder. At her criminal trial, Betty plead not guilty, stating that she had killed Willie in self defense. Betty claimed to be a victim of battered woman syndrome. This is a condition wherein a wife is so dependent on her husband, both financially and emotionally, and so afraid he will harm her if she leaves, that she finds herself unable to leave him, despite his violent behavior. Victims of battered woman syndrome may be inspired to finally kill their husbands, as they see this as their only means of escape.

The jury at Betty’s trial was instructed that Betty was responsible for providing enough evidence to back up her claim of self defense. Betty’s attorney objected to this, saying that it was unconstitutional to place this burden on Betty, rather than on the State. The objection was overruled, and Betty was ultimately convicted of aggravated murder. Betty appealed to the Court of Appeals of the County of Cuyahoga, and the Court affirmed her conviction. The Ohio Supreme Court dismissed her appeal.

Betty then sought a writ of certiorari from the U.S. Supreme Court, asking the Court to review the appellate court’s holding, arguing that the jury was improperly instructed, and to request that the State bear the burden of proof in her prosecution. The Court, however, denied her request.

Related Legal Terms and Issues

  • Affirmative Defense – The introduction of evidence in a trial that would negate, or “cancel out,” the defendant’s civil or criminal legal responsibility for the alleged act.
  • Aggressor – A person that attacks another person first.
  • Defendant – A party against whom a lawsuit has been filed in civil court, or who has been accused of, or charged with, a crime or offense.
  • Malice – The intention to do evil, inflict injury, or cause suffering of another.
  • Prosecution –The lawyer(s) who argue that a person who is accused of a crime is guilty.