House Bill 129 amends Tennessee Code Annotated, Title 58, Chapter 1, by introducing a new section that establishes conditions under which the Tennessee National Guard or its members can be released into active duty combat. The bill defines "active duty combat" as participation in armed conflict, hazardous service related to armed conflict in a foreign state, or duties through an instrumentality of war. It also defines "official declaration of war" as a declaration made by the United States Congress in accordance with the Constitution. The bill stipulates that the National Guard cannot be deployed into active duty combat unless there is an official declaration of war or specific congressional action to call them forth for certain purposes, such as executing laws, repelling invasions, or suppressing insurrections.

Additionally, the bill clarifies that it does not restrict the governor's authority to consent to the deployment of National Guard members for defense support for civil authority missions within the United States and its territories. This legislation aims to ensure that the deployment of the Tennessee National Guard aligns with federal constitutional requirements, thereby reinforcing the checks and balances regarding military engagement. The act will take effect upon becoming law.