In 1939, seven concerned members of the Missouri House of Representatives introduced a proposed constitutional amendment that would have created a system of non-partisan selection and retention for state judges. However, the House committee to which this proposal was assigned voted unfavorably, and the measure was not considered further.

In 1940, alarmed by the real and potential abuses inherent under the existing system, bar organizations and citizens' groups across Missouri began working together to develop a grass-roots campaign for an initiative petition to amend the state constitution. Led by the Missouri Institute for the Administration of Justice––a group composed of one-third lawyers and two-thirds other citizens––the effort gained support from civic, labor, farm and industrial organizations throughout the state. As a result of that initiative petition, a proposal to create non-partisan selection and retention methods in all state appellate courts, Jackson County and the City of St. Louis was placed on the November 5, 1940 general election ballot. When the vote totals were counted, the citizens of Missouri had approved the amendment by a margin of more than 80,000 votes.

However, in 1943, during the Missouri constitutional convention, a major effort was made to exclude the non-partisan court plan from the new constitution. The effort to exclude the plan failed, and it was eventually incorporated into the new state constitution.

Judges in St. Louis County came under the non-partisan plan in 1970, followed three years later by the judges of Clay County and Platte County.

The Kansas City Star, in an editorial many years ago, focused on the plan's legacy when it wrote: “A judge doesn't have to borrow and spend money to conduct a campaign. He is not forced to make political promises to men who control votes. He does not have to answer to a political boss, nor does he need to accept campaign contributions from lawyers who will practice in his court. It is by far the best plan yet devised to keep the bench out of partisan campaigns.”

Indeed, the "Missouri Plan" has since been adopted, in some form, in 34 other states.