Missouri Law on Assault with a Deadly Weapon: Understanding Your Rights and Defenses

Missouri laws on assault provide more substantial penalties for those involving “a deadly weapon or dangerous instrument.” That could mean not just a gun or knife but anything the defendant had at hand—a clear opportunity for prosecutors to overreach. Nonetheless, assault often results from complicated circumstances, allowing for several defenses under state law.

What Does Assault with a Deadly Weapon Mean in Missouri?

Categories of Assault

In Missouri, the law categorizes assault by degrees and by classes of felony or misdemeanor. Assault involving objects can be classified as:

• Assault in the second degree: “attempt[ing] to cause or knowingly caus[ing] physical injury to another person by means of a deadly weapon or dangerous instrument” (RSMo § 565.052(2))
  • Class D felony
• Assault in the fourth degree, when “with criminal negligence the person causes physical injury … by means of a firearm” (§ 565.056(1)(2))
  • Class A misdemeanor
• Domestic assault in the second degree, when the defendant “knowingly causes physical injury to [a] domestic victim by … use of a deadly weapon or dangerous instrument” or “recklessly causes injury … by means of any deadly weapon” (§ 565.073)
  • Class D felony
• Domestic assault in the fourth degree—causing injury “with criminal negligence … [with] a deadly weapon or dangerous instrument” or “purposely places [the victim] in apprehension of immediate physical injury” (§ 565.076)
  • Class A misdemeanor unless it is not the first domestic offense

Under state law, anyone guilty of a felony with a deadly weapon or dangerous instrument is also guilty of an “armed criminal action” or ACA. RSMo § 571.015. This means a mandatory minimum three-year sentence, and during that time, the prisoner is ineligible for parole, probation, suspension, or conditional release. 

Penalties

A class D felony—second-degree assault or domestic assault—carries a penalty of up to seven years in prison, together with possible fines. However, the court can decide to impose a one-year jail sentence for class D or E felonies. RSMo § 558.011. A class A misdemeanor can carry a jail term of up to one year.

Second-degree assault charges carry more severe penalties when the victim is a “special victim,” as Missouri law defines it. This includes the elderly, disabled people, vulnerable persons, and several types of public employees and workers, including law enforcement. See § 565.002(14). With a special victim, second-degree assault becomes a class B felony, which requires five to fifteen years in prison.

Defending a Charge of Assault: Definitions and Circumstance

The law takes armed assault seriously, but an experienced Missouri criminal defense attorney has several lines of attack that can reduce or even defeat assault charges.

Self-Defense

In Missouri, a person has the right to defend themselves, others, or their property through physical force if they “reasonably believe” that they are facing “use or imminent use of unlawful force.” RSMo § 563.031.

Even so, the defendant must show that they acted to avoid an imminent injury and were not responsible for the situation. See § 563.026. Only proportionate force is legal—deadly force is justified in very few circumstances.

Self-defense is not available if the defendant was the aggressor—if, in other words, “he started it.” Even so, if the defendant had already clearly backed down from their aggression, and the alleged victim continued to threaten force, self-defense is still a viable claim. See § 563.031(1)(a).

In Missouri, someone on their own property or anywhere else that they have a right to be has no duty to retreat from an aggressor. See § 563.031(3). If a defendant can show that they were in a place they had every right to remain and that they responded proportionately, out of reasonable fear, they may have a strong case for self-defense.

What Is a Dangerous Instrument?

Missouri law lists the weapons it considers “deadly.” See § 556.061(22). A dangerous instrument, however, is “any instrument, article or substance, which, under the circumstances … is readily capable of causing death or other serious physical injury.” Id. Pens, telephones, and even elbows have qualified as “dangerous instruments” in past cases. See 83 Mo. L. Rev. (2018). Nonetheless, a defense attorney can argue that the object involved could not, in fact, have caused death or injury under the circumstances, nor did the defendant think it could.

The Arrest and the Evidence

If the arrest was unlawful, the state may not be able to press charges. For a lawful arrest, an officer needs either probable cause or an arrest warrant. Probable cause requires reasonable grounds to believe that a defendant had committed a crime. See RSMo § 544.216. Similarly, to search someone without a warrant, an officer must have a reasonable suspicion—what they must suspect will vary under the circumstances.

If you have been charged with a crime, a defense attorney will examine every element of your encounter with the police, including their behavior throughout the arrest. Did they have reasonable suspicion? Was their search lawful? Did they inform the arrestee of their rights and respect those rights? When the police fail to perform a lawful arrest or search, the evidence may not be admissible in court, and the state’s case is likely to fail without it.

The Defense You Deserve

As a former prosecuting attorney, Kyle Loraine understands very well how prosecutors decide to charge defendants and how to find the weak points in their case. If you are facing assault or any criminal charges in Missouri, call Loraine Law Center today in Jefferson City 573-284-3048 or Kansas City (816-720-7634) for your free 30-minute consultation.