This chapter examines how civil liability assessments and criminal convictions have affected the legality of blood sports. Blood sports can be divided into three categories: human versus human contests, human versus animal sports, and animal versus animal fighting. For over a century, blood sports have been under both social and legal attack, resulting in significant changes in most of the historic forms of combat worldwide. The chapter begins with an overview of the most popular violent sports today, including contact sports such as American football and ice hockey. It then considers criminal prosecutions and civil lawsuits that arise from contact sports, including the “concussion suits” filed on behalf of athletes who suffered head injuries. It also discusses the doctrine of assumption of risk in sports and concludes with an analysis of how legislative intervention can obviate private tort liability for latent, chronic injuries to the brain of players.