In the United States v. Von Neumann case of 1985, the U.S. Supreme Court dealt with issues related to customs and forfeiture laws. The defendant, Von Neumann, had his car seized by U.S. Customs after failing to declare items he was bringing into the country from Mexico that were worth more than $400 - a violation of federal law. He sought relief under an exception in forfeiture law which allows for remission or mitigation if it is found that there was "reasonable cause" for the violation; however, this request must be made within 90 days following seizure. Von Neumann argued that he should have been notified about this time limit when his property was seized but wasn't informed until later on during legal proceedings – thus violating due process rights as per Fifth Amendment protections against deprivation of property without due process of law. However, the court ruled against him stating that while notice is required before government can deprive someone's interest in their property (as per Mullane v Central Hanover Bank & Trust Co), such notice does not need to include information about all possible remedies available under different circumstances.

The dissenting opinion in the United States v. Von Neumann case argued that the forfeiture of a vehicle used to transport undeclared goods across international borders was not proportional to the offense committed, and thus violated the Eighth Amendment's prohibition on excessive fines. The justice contended that while Mr. Von Neumann had indeed broken customs law by failing to declare his purchase of two Rolex watches upon reentering America from Mexico, this infraction did not warrant such an extreme punishment as losing his Mercedes-Benz car worth $39,000 at auction sale price or approximately $60,000 at replacement value. The dissent emphasized that there should be proportionality between crime and punishment; otherwise it would constitute cruel and unusual punishments prohibited under U.S constitution’s eighth amendment.