The standard set in Tennessee v. Garner requires that there be probable cause to believe a suspect poses a significant threat of death or serious physical injury to the officer and others, and that deadly force is necessary to prevent his escape. 'Deadly force' is defined, and case law is cited to illustrate. The substance and scope of the standard and its practical applications for law enforcement officers and agencies are discussed. Specifically, the 'seizure' and 'reasonableness' requirements, threats with a weapon, and probable cause are examined. Footnotes.