Controversy: No-knock warrants have been controversial for various reasons. Some consider them to be unconstitutional. In addition, there have been cases where burglars have robbed homes by pretending to be officers with a no knock warrant. In many cases, armed homeowners, believing that they are being invaded, have shot at officers, resulting in deaths on both sides. While it is legal to shoot a homeowner's dog when an officer fears for their life, there have been numerous high profile cases in which family pets lacking the size, strength, or demeanor to attack officers have been shot, greatly increasing the risk of additional casualties in neighboring houses via overpenetrating bullets. Police are criticized for the use of no-knock search warrants. A no-knock search warrant is a warrant which sanctions the entry of police officers into a residence and/or business without first knocking and announcing who they are and/or why they are entering the property. These warrants are authorized when a “knock-and-announce” search warrant would lead to the destruction of the evidence police are searching for and/or would compromise the safety of police and innocent civilians. The Fourth Amendment to the United States Constitution assures and protects individuals from unreasonable searches and seizures (U. S. Constitution). Police and/or criminals may interpret the phrase, “unreasonable searches and seizures,” in different ways. Police view unreasonable searches and seizures as entering a home or property without obtaining what is deemed as probable cause. Probable cause is based on the officer having reason to believe a crime has been committed or exigent circumstances defined in United States v. McConney: Emergency conditions. 'Those circumstances that would cause a reasonable person to believe that entry (or other relevant prompt action) was necessary to prevent physical harm to the officers or other persons, the destruction of relevant evidence, the escape of a suspect, or some other consequence improperly frustrating legitimate law enforcement efforts'". The Bill of Rights and Other Amendments". U. S. Constitution. N. p. , n. d. Web. 16 Nov. 2012. United States v. McConney, 728 F. 2d 1195, 1199 (9th Cir). , cert. denied, 469 U. S. 824 (1984)