Arson is the intentional burning of property—such as a building, car, boat, crops, or trees—with criminal or fraudulent intent. The criminal intent or motive behind arson is often insurance fraud—such as when the owner of property intentionally burns it and then files an insurance claim without disclosing the owner intentionally started the fire.

Arson is a felony offense under most state laws, but there are often different degrees of severity, depending on factors such as whether the fire results in physical injury or death. Arson is also a crime under federal law, which makes it illegal to use fire or an explosive to damage or destroy property used in interstate or foreign commerce, or in any activity affecting interstate or foreign commerce.

In Montana (MT), arson is defined as the willful and malicious burning or charring of property and is considered a serious felony offense. The state's laws distinguish between different degrees of arson based on factors such as the type of property involved, whether the property was occupied, and whether the act resulted in bodily injury or death. For example, arson that endangers human life is treated more severely than arson affecting uninhabited property. The motive behind arson, such as insurance fraud, can also influence the severity of the charges and penalties. Insurance fraud involving arson is a separate criminal offense and is prosecuted vigorously. Additionally, under federal law, arson is illegal when it involves property used in interstate or foreign commerce, or affects any activity involving interstate or foreign commerce. Penalties for arson under federal law can be severe, especially when the arson results in injury, death, or significant damage to property.