FEMA has a tutorial that you can access on the web:
GUIDE TO EMERGENCY MANAGEMENT AND RELATED TERMS, DEFINITIONS, CONCEPTS, ACRONYMS, ORGANIZATIONS, PROGRAMS, GUIDANCE & LEGISLATION
BELOW ARE SOME KEY DEFINITIONS FROM THIS DOCUMENT
Civil Disturbance: “Group acts of violence and disorder prejudicial to public law and order.” (DOD Dictionary of Military and Related Terms, 2007)
Civil Disturbance Readiness Conditions: “Required conditions of preparedness to be attained by military forces in preparation for deployment to an objective area in response to an actual or threatened civil disturbance.” (DOD Dictionary of Military and Related Terms, 2007)
Civil Disturbances: “Group acts of violence and disorders prejudicial to public law and order within the 50 States, District of Columbia, Commonwealth of Puerto Rico, U.S. possessions and territories, or any political subdivision thereof. As more specifically defined in DoD Directive 3025.12 (Military Support to Civil Authorities), “civil disturbance” includes all domestic conditions requiring the use of Federal Armed Forces.” (DoD, MACDIS, 1994, p. 17; Title 32 CFR 185)
Civil Disturbance Operations. “The President has the authority to deploy troops within the United States to enforce the laws. The Enforcement of the Laws to Restore Public Order, Chapter 15 of Title 10 USC (formerly Insurrection Act) authorizes the President to employ the Armed Forces of the US, including the NG, within the United States to restore order or enforce federal law after a major public emergency (e.g., natural disaster, serious public health emergency, or terrorist attack) when requested by the state governor or when the President determines that the authorities of the state are incapable of maintaining public order. The President normally executes his authority by ordering the dispersal of those obstructing the enforcement of the laws. The President may act unilaterally to suppress an insurrection or domestic violation without the request or authority of the state/governor and to exercise his “major public emergencies” authority to direct the SecDef to provide supplies, services, and equipment necessary for the immediate preservation of life and property. Such supplies, services, and equipment may be provided: only to the extent that the constituted authorities of the state or possession are unable to provide them; only until such authorities and other departments and agencies of the United States charged with such responsibilities are able to provide them; and only to the extent that their provision, in the judgment of the SecDef, will not interfere with the preparedness of ongoing military operations or functions. Responsibility for the coordination of the federal response for civil disturbances rests with the Attorney General. Any DOD forces employed in civil disturbance operations shall remain under military authority at all times. Forces deployed to assist federal and local authorities during times of civil disturbance follow the use-of-force policy found in CJCS Instruction (CJCSI) 3121.01B, Standing Rules of Engagement/Standing Rules for the Use of Force for US Forces.” (JCS/DoD, Civil Support, 2007, pp. III-4-5)
Insurrection Act: “The Insurrection Act governs when the President can declare a form of martial law. When the act is invoked, the military, including the National Guard, can carry out law enforcement functions without the consent of a Governor . Posse comitatus, a broad law that generally prevents the military from policing within the domestic United States, does not apply when the act is invoked.- Advertisement -
Until the “Insurrection Act Rider” was enacted in the fall of 2006, U.S. law focused on enabling the President to invoke the Insurrection Act during violent situations where the states or local communities were resisting lawful orders. The intent of the law, as the title suggests, was to deal with insurrection from individuals or groups. The law was not designed to address other situations, including natural disasters, or attacks from outside the country.
In its original form, the Act has been invoked sparingly -- only ten times in the past five decades. Over the past 40 years, the act has only been invoked with the consent of the governors, using authorities under other sections of the U.S. Code that allow states to invite in federal military forces for police functions.
Under the new language, added to the law in the fall of 2006, the President can invoke the act and declare martial law in cases where public order breaks down as a result of a natural disaster, epidemic, terrorist attack, or under the nebulous term of “other conditions."
This change makes it easier for the President to invoke the Act in cases beyond an insurrection – cases which were not intended under the previous purpose of the Act. With these succinct but sweeping changes, the President now does not have to contact or collaborate with any state agency in taking control of the Guard and injecting federal military forces, to carry out patrols or make arrests. The President has to notify but not explain to Congress that he or she believes that states cannot handle the situation.
The change goes against practical and historical arrangements for handling emergencies, which constitutionally and practically have been headed and handled by governors and local officials. When operating under a governor in a state status, the National Guard is not bound by posse comitatus and can integrate seamlessly with local, state, and federal law enforcement agencies and first responders.” (Leahy, “Insurrection Act,” 2007)
Insurrection Act: “The Insurrection Act (enacted in 1807) delegates authority to the President to federalize and deploy the National Guard domestically during an insurrection or civil disturbance (10 U.S.C. Sections 331-335). Section 331 authorizes the President to use federal military forces to suppress an insurrection at the request of a state government. Section 332 authorizes the President to use armed forces in such manner as he deems necessary to enforce the laws or suppress a rebellion. Section 333 authorizes the President to use federal military forces to protect individuals from unlawful actions that obstruct the execution of federal laws or which impede the course of justice under federal laws. Section 333 was enacted to implement the Fourteenth Amendment and does not require the request or consent of the governor of the affected state.” (Lowenberg, “Statement by Major General Timothy Lowenberg, April 24, 2007)
Insurrection Act Rider of 2006: [Section 1076 of the 2007 National Defense Authorization Act (Public Law 109-364), 2006.]