It is extremely important to understand that the fact that a defender is not charged in the criminal justice system does not mean that he or she has met the standard for justification to prevent civil liability. Nor does an acquittal in criminal court automatically establish civil immunity; and depending upon the laws of the jurisdiction, acquittal in criminal court may indeed fall far short of protecting a defendant from civil liability.
On the criminal side, the burden of proof for justifying the use of force varies among jurisdictions. In some states, such as New York, to cite only one example, a defendant who clams self defense must convince the triers of fact that the act was lawfully justified by showing by a preponderance of the evidence that all of the elements of lawful self defense had been present. In others, such as Arizona, Florida, and West Virginia, the state must prove beyond a reasonable doubt that the defender’s act was not justified. Thus, a prosecutor who believes that he or she would be unlikely to meet the BARD threshold may choose to not charge a suspect. Or if charges are filed, the state may fail to get a conviction.
The first outcome would not meet the standard for civil immunity--nothing has been proven. Nor would the second, in a state in a jurisdiction in which the state would be required to prove beyond a reasonable doubt that the defendant had not acted in lawful self defense. In a civil trial, only a preponderance of the evidence is necessary to support a judgment against a defendant. Put another way, unless more of the evidence supports justification than liability, the judgment will go against the defendant. In some jurisdictions, the burden of proof for the state in a criminal trial involving a claim of justified self defense is much greater than that for a plaintiff in a civil trial.