The case of  Garner v. Tennessee 471 U.S. 1 (1985)

The case of Garner v. Tennessee is not a self defense case for civilians.  Instead this is the standard for the use of deadly force by police in apprehension of felons.  But it is often cited as a self defense case and the principles are similar. 

Garner is a case about police liability for the use of excessive force (deadly force) in making an arrest.   It stands for the proposition that deadly force is only proper in defense of life and not property.   Although Garner the same principles and analogy it is not a civilian self defense case.  The Court expects police to protect themselves and the public and to use any necessary and reasonable force to make arrests.  But using Deadly Force on someone who is unarmed, of little threat and escaping for a mere property crime is not a proper level of force.  

Garner was a teenager who was shot by an officer while escaping from a burglary.   There was no indication that he was armed or dangerous and Garner was a youth.  The officer was sued under a US statute §1983 for civil damages.   This case cites 3 principles or requirements for the use of deadly force. 

(1) the officer must have probable cause to believe that the suspect has committed a crime involving the infliction or threatened infliction of serious physical harm;

(2) The use of deadly force is NECESSARY to prevent escape;

The last principle was that warnings should be given when appropriate.  However it is almost never appropriate to take the time to give a warning under the conditions of self defense or to use warning shots.   Warning shots nearly always place innocent bystanders in danger.   This case was ruled upon the issues of: 1983 liability and Police Misconduct and not the use of deadly force in self defense but the principles are the same issues in a self defense case.  Here is 18 USC 242 and 42 USC 1983

 Every situation is different however and this is for information only.  This is not legal advice.