In the case of Schneckloth, Conservation Center Superintendent v. Bustamonte in 1972, the U.S Supreme Court ruled that law enforcement officers do not need to inform individuals of their right to refuse consent when asking for permission to conduct a warrantless search. The court held that while knowledge of the right to refuse is one factor taken into account in determining whether or not a person has voluntarily given consent, it is not necessary for an individual's consent to be considered valid under the Fourth Amendment. Instead, voluntariness should be determined from all circumstances surrounding giving of consent and no single criterion controls whether an individual’s act was voluntary; courts must look at "totality" of facts involved.

In the dissenting opinion for Schneckloth v. Bustamonte, Justice Thurgood Marshall argued that consent to a search must be both knowing and intelligent in order to satisfy the Fourth Amendment's requirement of reasonableness. He disagreed with the majority's view that voluntariness should be determined by examining all circumstances surrounding a case without any need for demonstrating knowledge of rights. Instead, he believed that individuals should have an understanding of their right to refuse consent before it can truly be considered voluntary. This would require police officers to inform people about this right prior to seeking their permission for searches - similar to how suspects are read their Miranda rights upon arrest. Without such awareness, Justice Marshall contended, many might feel compelled or intimidated into granting access due simply not knowing they could legally decline.