when is an officer justified in using deadly force
Deadly force The United States Armed Forces defines deadly force as "force that a person uses causing, or that a person knows or should know would create a substantial risk of causing, death or serious bodily harm or injury".[2][1] In the United States, the use of deadly force by sworn law enforcement officers is lawful when the officer reasonably believes the subject poses a significant threat of serious bodily injury or death to themselves or others. The use of deadly force by law enforcement is also lawful when used to prevent the escape of a fleeing felon when the officer believes escape would pose a significant threat of serious bodily injury or death to members of the public. Common law allowed officers to use any force necessary to effect a felony arrest but this was narrowed in the Tennessee v. Garner ruling in 1985 when the U.S. Supreme Court said that "deadly force...may not be used unless necessary to prevent the escape and the officer has probable cause to believe that the suspect poses a significant threat of death or serious bodily harm to the officer or others." [1]
United States free speech exceptions The Supreme Court has held that "advocacy of the use of force" is unprotected when it is "directed to inciting or producing imminent lawless action" and is "likely to incite or produce such action".[1][2] In Brandenburg v. Ohio (1969), the Supreme Court unanimously reversed the conviction of a Ku Klux Klan group for "advocating ... violence ... as a means of accomplishing political reform" because their statements at a rally did not express an immediate, or imminent intent to do violence.[3] This rule amended a previous decision of the Court, in Schenck v. United States (1919), which simply decided that a "clear and present danger" could justify a congressional rule limiting speech. The primary distinction is that the latter test does not criminalize "mere advocacy".[4]