Based on human genetic makeup, the test can match human cells in hair, blood, and semen found at the scene of the crime with the cells of a suspect. Court cases addressing physician-patient and lawyer-client privileges are discussed. Decisions regarding witnesses address such issues as impeachment, expert testimony, hypnosis, identification, and the Sandoval Rule which bars the defendant and prosecution from using prior crimes against a codefendant. Regarding presumptions from predicate facts, New York Penal Law provides that a person who operates a vehicle without the consent of the owner is presumed to know he has no consent. A case is presented concerning the preservation of real evidence for purposes of defense testing. Circumstantial evidence concerning other crimes, habitual conduct, and subsequent repairs (other accidents) is examined. General hearsay evidence, state of mind, declaration against interest and admissions, prior testimony, and business records are also addressed. 284 footnotes