62S The speed, intensity, and aggressiveness of the game of football have increased over the past decades, especially at the professional level. The incidence of injury in modern top-level football matches is high, 12,13 and the overall risk of injury to professional players is about 1000 times higher than for industrial occupations. 12 Furthermore, Drawer and Fuller showed that the risk associated with acute injuries is unacceptable when evaluated against work- based criteria. 6 Football is a contact sport, and 42% to 74% of the acute injuries are considered a result of physical con- tact between players. 3,7,10,13,20,21,23 Previous studies have shown that tackling is the primary mechanism of nearly half of the anterior cruciate ligament (ACL) injuries 4 and most of the sprain injuries 3 in both the ankle and knee. 7,21 Studies on prevention of football injuries are few, 5,9,14,18,24–26 and one explanation for the paucity might be the lack of solid evidence about the risk factors and mechanisms for football injuries at different levels of play. In several studies at lower levels, foul play has been proposed to be the most important cause of injury. 8,20,21,23 Hawkins and Fuller 10,11 showed that 15% to 29% of all injuries at the inter- national and elite levels resulted from foul play, whereas the rest of the injuries occurred without a free kick being awarded by the referee. In all the nonfoul situations in which injury resulted, at least 60% still involved player-to-player contact, and it is not known whether referee performance was ade- quate in these cases. Since reduction of foul play and obser- vance of the existing laws of the game have been proposed as possible interventions to reduce the rate of injuries, 8 it is important to assess how the laws of the game are being applied by the referees in injury situations. Thus, the aims of this study were primarily to evaluate how violations of the laws of the game contribute to injury in football and, secondarily, to investigate whether the decisions made by the referees were correct according to the laws of the game of football in situations with a high risk of injury. METHODS Videotapes and injury information were collected prospec- tively for the regular league matches during the 2000 Rule Violations as a Cause of Injuries in Male Norwegian Professional Football Are the Referees Doing Their Job? Thor Einar Andersen,* MD, Lars Engebretsen, MD, PhD, and Roald Bahr, MD, PhD From the Oslo Sports Trauma Research Center, Norwegian University of Sport and Physical Education, Olso, Norway Background: Foul play is an important cause of injury in football. Reduction of foul play and adherence to the laws of the game may be possible interventions to reduce the rate of injuries. Purpose: To evaluate how violations of the laws of the game contribute to injury and to investigate whether the decisions made by the referees are correct in high-risk situations. Study Design: Prospective cohort study. Methods: Videotapes and injury information were collected for 174 of 182 matches from the male Norwegian professional league during the 2000 season. Three Norwegian FIFA referees performed retrospective blinded evaluation of the 406 incidents. Results: Less than one-third of the injuries identified on video and about 40% of the incidents with a high risk of injury resulted in a free kick being awarded. About 1 in 10 of these situations led to either a yellow or red card. The agreement between deci- sions made by the match referee and the expert referee panel was good, that is, their decisions agreed in 85% of the situations in which injury occurred. Conclusions: There may be a need for an improvement of the laws of the game of football to protect players from dangerous play. Keywords: football injuries; injury mechanisms; prevention; video recording * Address correspondence and reprint requests to Thor Einar Andersen, Oslo Sports Trauma Research Center, Norwegian University of Sport and Physical Education, P.O. Box 4014 US, Oslo 0806, Norway. The American Journal of Sports Medicine, Vol. 32, No. 1 Suppl. DOI: 10.1177/0363546503261412 © 2004 American Orthopaedic Society for Sports Medicine