In the United States v. Johnson case of 1965, the U.S. Supreme Court ruled that a congressional committee had violated defendant Walter L. Johnson's Fifth Amendment rights by compelling him to testify about his Communist affiliations and activities without offering immunity from prosecution for any crimes he might admit during his testimony. The court held that Congress could not force an individual to incriminate themselves unless they were granted immunity from prosecution based on their testimony, upholding the principle of protection against self-incrimination enshrined in the Constitution. This decision significantly limited Congress' power to investigate individuals suspected of subversive activities and reaffirmed citizens' constitutional protections even when national security concerns are at stake.

In the dissenting opinion for United States v. Johnson, Justice Harlan argued that the Court's decision to exclude evidence obtained through wiretapping was a misinterpretation of Rule 41(e) and an overextension of its authority. He contended that Congress had not intended for this rule to apply in situations where law enforcement officials acted in good faith under a warrant they believed to be valid. Furthermore, he pointed out that no constitutional rights were violated since there was no unreasonable search or seizure involved - the wiretap order was issued by a competent federal judge based on sufficient evidence demonstrating probable cause. Therefore, according to Justice Harlan, excluding such crucial evidence would only serve as an unnecessary hindrance to effective law enforcement without providing any substantial protection against potential abuses of power.