Dean Brothers Corp. owns and operates a steel-drum manufacturing plant. Lowell Wyden, the plant superintendent, hired Best Security Patrol, Inc. (BSP), a security comapny, to guard the property and "deter thieves and vandals." Some BSP security guards, as Wyden knew, carried firearms. Pete Sidell, a SP security guard, was not certified as an armed guard but nevertheless took his gun to work. While working at the Dean plant on October 31, Sidell fired his gun at Tyrone Gaines, in the belief that Gaines was an intruder. The bullet struck and killed Gaines. Gaines's mother filed a lawsuit claiming that her son's death was the result of BSP's negligence, for which Dean was responsible.

(1) What is the Plaintiff's best argument to establish that Dean was responsible for Sidell?

(2) What is Dean's best defense against liability?