One of the most common reasons that a firm may choose to take on contingency cases is to file mass tort lawsuits. When a law firm accepts contingency cases they agree to work on a contingency basis. Working on contingency means that the plaintiff will not pay for any legal fees until the case is either settled or won. At that time, the law firm will usually take a percentage of the compensation recovered. This means that if the plaintiff does not win their case, the law firm does not collect any fees for their services. Many law firms may work on contingency if it seems like the plaintiff cannot afford legal support but has a solid or provable case.