The U.S. Supreme Court case Guaranty Trust and Safe Deposit Company v. Green Cove Springs and Melrose Railroad Company in 1890 revolved around a dispute over the payment of bonds issued by the railroad company, which were secured by a mortgage on its property. The plaintiff, Guaranty Trust and Safe Deposit Company, was acting as trustee for bondholders who had not been paid interest due on their bonds. They sought to foreclose on the mortgage to recover these payments. However, there was disagreement about whether Florida law or federal law should apply in determining how foreclosure proceedings should be conducted - specifically regarding notice requirements for selling mortgaged properties under foreclosure decree. The court ruled that while state laws generally govern such procedures unless they impair rights or remedies under federal statutes; it found no impairment here because Florida's requirement of public advertisement before sale did not conflict with any provision of federal law applicable to this case nor deprive plaintiffs from realizing their security effectively.

The dissenting opinion in the case of Guaranty Trust and Safe Deposit Company v. Green Cove Springs and Melrose Railroad Company argued that the majority's decision to uphold a lower court ruling, which allowed for foreclosure on a mortgage held by Guaranty Trust against Green Cove Springs, was incorrect. The dissent contended that this violated principles of equity because it did not take into account whether or not there were other creditors with claims against the railroad company who could be harmed by such an action. They believed that all parties involved should have been given notice and opportunity to present their claims before any foreclosure proceedings took place. Furthermore, they disagreed with the majority’s interpretation of Florida law regarding mortgages on railroads; arguing instead that under state law, these types of mortgages are considered subordinate to liens for labor and materials used in construction or operation of said railroads.