The U.S. Supreme Court case Green County, Kentucky v. Thomas' Executor in 1908 revolved around a dispute over the payment of bonds issued by Green County to fund railroad construction under an act passed by the state legislature. The county refused to pay on these bonds after it was determined that they were illegally issued due to a lack of public vote as required by law. However, bondholders argued that since they had purchased them in good faith and without knowledge of any irregularities, they should be paid regardless. The court ruled against Green County stating that even though the issuance may have been illegal initially, this did not absolve the county from its obligation towards those who bought these bonds unaware of their illegality at time of purchase. This ruling upheld principles related to negotiable instruments and reinforced investor confidence in such securities.

In the dissenting opinion for Green County, Kentucky v. Thomas' Executor, Justice Harlan disagreed with the majority's decision to deny Green County its claim on a bond issued by it and held by Thomas' estate. He argued that there was no legal basis for denying this claim as the county had not defaulted on any payments related to this bond nor had it repudiated them in any way. Furthermore, he contended that if such bonds were deemed unenforceable due to their potential misuse or abuse then all public securities could be rendered worthless which would have serious implications for public finance and trust in government institutions. Therefore, he believed that upholding the enforceability of these bonds was essential even if they may have been used improperly in some instances.