The term 'REASON TO SUE' can be summarized by the crossword solution of 'TORT, ' which is a legal term for a wrongful act or an infringement of a right that leads to civil legal liability. A TORT is a civil wrong that can be the basis for a lawsuit, and it can involve intentional or unintentional harm to another person or their property. In a lawsuit, the plaintiff must prove that the defendant's actions were the cause of the harm in order to receive compensation.