This chapter addresses two major themes: first, the development and challenges of multi-party actions; and, secondly, the principles and case law of negligence and nervous shock in the 20th century, including post-traumatic stress disorder, viewed through a policy lens. Mass actions arising out of disasters are part of a high-profile event, conducted in the public arena with significant media coverage, which, along with the pooling of expertise and resources, appears to give an impression of power and strength in numbers compared to individual claims for negligence.