It is entirely appropriate that the Bill of Rights has a provision addressing the individual citizen's right to privacy from government authorities. The authors of the Constitution knew how vitally important it was to protect citizens from violations of their privacy, especially with respect to invasions of their homes by agents of the government. It was in this context that the Fourth Amendment to the Constitution was drafted, debated, and ratified. That amendment reads as follows:
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
The difficulties of policing a modern society and prosecuting criminal cases through the judicial system might suggest that the most speedy means of assembling a strong case against a defendant is best. Investigating officers who, in the course of doing their job, might view illegal items (ex: unregistered guns, drugs, etc) would naturally want to seize those items. The problem, however, is that these seizures may very well violate the wording and the spirit of the Fourth Amendment.
There have been quite a number of major court cases decided by the U.S. Supreme Court regarding the ability of law enforcement officers (and others, like school principals--Safford v. Redding, 2009) to seize evidence. Of particular interest happens to be one of the earliest of these decisions, Weeks v. United States. In this 1914 decision, the Supreme Court formally outlined what became known as "the exclusionary rule." The exclusionary rule is meant to discourage law enforcement from conducting illegal searches by stating that any evidence found in an illegal search cannot be used against the defendant in court. This decision represented one of the most important applications of the Fourth Amendment in the nation's history. In this particular case, police had searched and gathered evidence from Fremont Weeks' home without a warrant (court issued permission to search someone's property). The Supreme Court ultimately ruled that, because the evidence used to prosecute Weeks had been obtained without a proper warrant, it was inadmissible in court.
The question, then, is about impact on law enforcement's ability to execute their mission despite a series of Supreme Court decisions that have limited their ability to intrude on the privacy of others. Though the use of the "exclusionary rule" has resulted in the overturning of convictions and consequent release of "criminals," there is little to suggest that public safety has been threatened by the Courts' rulings. Of course, you can argue that the Fourth Amendment and of the Exclusionary Rule have, in some cases, undermined criminal investigations and potential prosecutions. The requirement for a properly obtained warrant, however, is a bedrock of American justice. (Additionally, history has clearly demonstrated that successful prosecutions can be built through the use of court-sanctioned warrants.)
There is little or no evidence that the Fourth Amendment and the Exclusionary Rule have impaired public safety. Though police might enjoy a legal system that allowed for warrantless searches, we can all recognize that the Bill of Rights, while subject to interpretation, is, or should be, absolute.