The United States v. Lovasco case in 1976 revolved around the issue of whether a delay between the commission of a crime and indictment infringes on due process rights under the Fifth Amendment. Michael J. Lovasco was indicted for unlawful possession of firearms, eighteen months after federal agents had gathered enough evidence to charge him. He argued that this delay violated his right to due process as it potentially weakened his defense by allowing memories to fade and evidence to be lost over time. However, the Supreme Court ruled against Lovasco in an 8-1 decision stating that proof of prejudice is necessary for such claims; mere speculation about potential harm isn't sufficient grounds for dismissal of charges based on delayed prosecution. The court held that prosecutors are not constitutionally obligated to file charges as soon as probable cause exists but can wait until they feel they have enough evidence for conviction beyond reasonable doubt.

In the dissenting opinion for United States v. Lovasco, Justice Marshall argued that the majority's decision failed to adequately protect a defendant's right to a speedy trial as guaranteed by the Sixth Amendment. He contended that an 18-month delay between investigation and indictment was unreasonable and potentially prejudicial against defendants, even if no specific prejudice could be demonstrated in this particular case. According to him, such delays can cause anxiety and concern for accused individuals while also increasing the risk of lost evidence or faded memories which may hinder their defense strategy. Furthermore, he criticized the majority’s reliance on prosecutorial discretion in deciding when to file charges after completing investigations because it leaves room for potential abuse of power without any clear legal standards or safeguards.