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. Among other measures to which Lindsey contributed his influence were a reform of the registration law, greatly reducing election frauds; a reform of the
ballot; state provisions for the support of the dependents of people serving in
prison; extension of the
probation system for prisoners; organization of public baths and playgrounds in Denver; the
institution of the fresh-air movement in Denver; and enactment of statewide Mother's Pension Law. He was a leader in the movement to abolish
child labor. He carried on an active
propaganda for the general adoption of the juvenile court plan, and for political and social reform, through
lectures delivered in many American and foreign cities and through the publication of books and pamphlets, of which
The Beast (with
Harvey J. O'Higgins, 1910) was widely circulated. In 1906, Lindsey was a candidate for
governor of Colorado, and in 1912 became a member of the Progressive National Committee. ==Companionate marriage==