It depends upon the particular state and county in question. For example, some states have statutes that secure a property right for landowners to conduct prescribed fires. Contact your county Extension agent, local fire department, or state prescribed fire council for specific laws and regulations regarding prescribed fires in your area.
The liability issue of an escaped prescribed fire goes back to individual state laws, and each state is different. Several states have a prescribed burning act that protects prescribed burners from liability as long as they follow the guidelines of the law. Other states have strict liability laws which state that if the fire escapes, the person setting the fire is liable no matter what precautions were taken. Consult and understand your state laws and regulations before conducting a prescribed fire. Check with your state prescribed fire council for additional guidance or to learn about enacting a prescribed burning act as described above (Coalition of Prescribed Fire Councils).