This is my torts transferred intent definition. I believe it's from Talmage v. Smithwhether the P may recover depends upon an intention on the part of the D to hit someone or to inflict an unwarranted injury upon somebody. the fact that the D injured someone though not intended does not relieve him of responsibility.
I was just grappling with the reason for it - it's completely public policy. How could it be an intentional if I aimed at A and I hit B? I did not "intend" to hit B, nor was I substantially certain I would hit B!