Lindsey was a pioneer in the establishment of the juvenile court system. Through his efforts, an act was passed creating a juvenile court in Denver which represented an important advance in relation of the law to children and would go on to serve as a model for future juvenile courts across America. Lindsey was made judge of the juvenile court in 1901 (which became a juvenile and family relations court in 1907). He held the position continuously, but he was not endorsed by either political party in 1908.