Efficient Cause
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
The working cause; that cause which produces effects or results; an intervening cause, which produces results which would not have come to pass except for its interposition, and for which, therefore, the person who set in motion the original chain of causes is not responsible.
Co.ntral Coal & Iron Co., v. Pearce (Ky.) 80 S. W. 450; Pullman Palace Car Co. v. Laack, 148 III. 242, 32 N. E. 285, 18 L. R. A. 215.