In Mitchell v. Gonzales, 54 Cal. 3d 1041, 1 Cal. Rptr. 2d 913, 819 P.2d 872, 878-79 (Cal. 1991) the Court reasoned that "BAJI Nos. 3.75 and 3.76 are alternative instructions that should not jointly be given in a single lawsuit." Id. at 876. Moreover, the "but for" test should not be employed when two "causes concur to bring about an event and either one of them operating alone could have been sufficient to cause the result." Id. The proper rule in those instances is to apply the substantial factor instruction which subsumes the "but for" test. Id. "If the conduct which is claimed to have caused the injury had nothing at all to do with the injuries, it could not be said that the conduct was a factor, let alone a substantial factor, in the production of the injuries." Id. at 878.