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In many claims in tort, or prosecutions in criminal law, the causal relationship between the defendant's wrongdoing and the victim's loss or injury is perfectly clear. If A hits B over the head, and B sustains a concussion, there is no real issue of causation. Problems arise in this area when the causal relationship is not direct. If A hits B over the head lightly, causing B to slip on a banana skin, and B then bangs his head on the pavement, is A liable? What if the banana skin had been carelessly discarded in an area where dropping banana skins was itself a criminal offense -- could it be that liability should be attributed to the banana-skin-dropper instead? Problems like this have taxed the courts for decades. For a discussion of the issues in criminal law, see causation in criminal liability; in tort see Causation In Tort.