Illinois assessors had to sign an oath before they could begin their duties. This image was taken from an 1862 assessor’s book for Hancock County, Illinois and includes the oath assessors were to take.
An 1853 Illinois act required assessors to sign an oath to uphold the Constitution and not to be involved in dueling.
Maybe the anti-dueling statement was to minimize difficulties over assessed values <grin!>.
This was a purchase I made on Ebay. It’s being donated to the Illinois Regional Depository at Western Illinois University in Macomb, Illinois.