The effect of contributory negligence in civic liability has always one of the important issues that considering its forms and norms needs to be discussed in different legal systems.Considering the issues and the concerned materials it can be understood that in Iran there is no a unity of standard about the field of contributory negligence. Also there is dispersion of ideas among the lawyers. This book aims to compare and deduce results by comparing the laws of different countries with the laws in Iran and Islam.According to the Islamic rules, when the loser shares blame in loss, acting to his loss intentionally, no one is to pay as compensation. However according to the common law the share of the loser in such a case is considered in measuring the liability. Thus considering the points above, and the internal law, we intend to investigate the amount of the share that the loser shares along with different other factors considering the portion of the effect and involvement.