Let's consider this case.
John and Bill works together for apartment reparation in 10th floor. John unintentionally put big heavy hammer near the open window, after 5 minutes Bill accidentally (unintentionally) hit this hammer and it fall down from 10th floor and killed somebody.
Both of them went to court. Let's say we have ideal case. Everybody accept this story. There is no doubt that it was accident. John confirm, yes, I unintentionally put hammer near windows, Bill confirm yes, I accidentally (unintentionally) hit hammer and it fall down.
Theoretically if John would not put this hammer near the window, Bill would not drop it down and nobody would be killed. In this sense John is guilty.
From other side if Bill would be more careful and would not drop this hammer also nobody would not be killed. In this sense Bill is guilty.
My question: If it is classified as "Negligent homicide", What normal judge in Western World will decide about this case? Who is guilty and who will go to jail? John, Bill or both?
If both are guilty, will they have the same responsibility, like 5 years in jail for john and 5 years in jail for Bill or Bill will get more?
If it is difficult with criminal-law, let's say hammer fall down to the car and let's assume nobody has insurance. Who will pay for the car reparation in this case? John, Bill or both? and if both, each will pay 50% or different?