The Missouri Constitution of 1865, passed at the end of the Civil War when Radical Republicanism was at its zenith in the state, completely disenfranchised unrepentant Southern sympathizers. Usually called the Drake Constitution after its chief proponent, Charles D. Drake, the constitution provided that anyone who had ever been in Confederate service or who had openly sympathized with the rebellion could not vote, hold office, serve on a jury, or hold certain important jobs like teacher, preacher, or lawyer without first taking an oath of allegiance to the United States. Many unrepentant Rebels, of course, were unable in good conscience or unwilling to take such an oath.

The Missouri Constitution of 1865, passed at the end of the Civil War when Radical Republicanism was at its zenith in the state, completely disenfranchised unrepentant Southern sympathizers. Usually called the Drake Constitution after its chief proponent, Charles D. Drake, the constitution provided that anyone who had ever been in Confederate service or who had openly sympathized with the rebellion could not vote, hold office, serve on a jury, or hold certain important jobs like teacher, preacher, or lawyer without first taking an oath of allegiance to the United States. Many unrepentant Rebels, of course, were unable in good conscience or unwilling to take such an oath.
 One of the most amazing things to me about the Drake Constitution is that, even with strong Southern sympathizers barred from voting, it barely passed when put to a statewide vote in June of 1865. Obviously there were a lot of conservative and fair-minded Union people who didn't feel it was right to punish a person for what he believed or had believed in the past. There were just enough Radicals, though, to get the constitution passed into law. I can, to a certain extent, understand the punitive feeling of the Radicals who pushed the new constitution into law. If I had been a strong Union sympathizer during the Civil War, I would have found it hard to immediately start welcoming back with open arms the people who had wanted to rend the country asunder.
However, the practical effect of the Drake Constitution was merely to deepen and prolong the bitterness that had torn the country apart in the first place. It is hard to overstate the level of resentment the law engendered among those who had supported the Southern side during the war.
In a few cases, the Drake Constitution even led directly to violent incidents, such as the murder of the Rev. Samuel S. Headlee, a Southern sympathizer who was killed when, without having taken an oath of allegiance, he tried to preach at Pleasant View Church just across the Greene County line in Webster County (near present-day Elkland) in the summer of 1866. He wanted to restore the congregation, which had re-aligned with the Methodist Episcopal Church North during the war, to the southern branch of the M. E. Church, and he was shot down when he showed up to carry through with his announced intention.
The Headlee case was a relative rarity. The Drake Constitution usually did not play a role in the actual commission of a crime, but it often affected the outcome of criminal cases once they reached the courts. An example was Wild Bill Hickok’s killing of Dave Tutt in a gunfight on the Springfield square in the summer of 1865. The two men were friends, and the Drake Constitution had nothing to do with their disagreement. However, once Hickok, a former Union detective and scout, went to trial on a charge of manslaughter, the cards were all stacked in his favor, thanks to the Drake Constitution, and he was readily acquitted, despite the fact he had provoked the showdown by lying in wait for Tutt.  
Fortunately the Drake Constitution didn't last very long. By the early 1870s, the most objectionable provisions of the document were already being repealed.

Larry Wood writes a column for the Neosho Daily News.