Take, for example, the various shifts that led to the explosion in tort cases. Some of the old policies really were problematic, or at least debatable. The rule of contributory negligence held that if your own negligence contributed to a problem, you could not sue someone else who had been negligent as well. This had the advantage of keeping many cases out of the courts — but if the negligence of two people injures one of them, why should the non-injured party get off scot-free?
Or, say a company sells a product in good faith, and follows the law in doing so. Years later, it turns out that the product causes cancer. It hardly seems fair for the company to have to pay for its customers’ medical bills; but it’s no more fair for the customers to have to pay, as they did under the old system. It was self-interested, but hardly unreasonable, for lawyers to suggest that the deep-pocketed company should foot the bill.