This interpretation did little to protect individual privacy and led to the effective and confident use of such investigative techniques as electronic or physical surveillance. In Katz vs. United States, the court redefined search in terms of personal rather than physical trespass, emphasizing the concept of reasonable expectation of privacy. This redefinition resulted in confusion for law enforcement personnel and a loss of confidence in techniques such as warrantless entries into open fields, the inspection of discarded trash, flyovers, field tests, and dog sniffs. Recent decisions have served to clear some of this confusion. While not intended to diminish fourth amendment protections, these decisions have cleared the way for the use of traditional investigative techniques. The court has repeatedly emphasized both the importance of complying with fourth amendment proscriptions and the desirability of obtaining a warrant whenever possible. However, in situations where reliance on a warrant is not possible, it has approved the warrantless use of those investigative methods that merely intrude into areas that society is not willing to protect. As a result police can return to traditional practices with renewed confidence in the constitutionality of their actions. 56 footnotes.