Example #2-
Kyllo v. United States 533 U.S. 27 (2001)[1], was a United States Supreme Court case that held that the use of a thermal imaging device to detect heat emanating from a house constituted a search under the Fourth Amendment, therefore requiring police to obtain a search warrant.


Facts
Danny Lee Kyllo had been charged and convicted with growing marijuana in his Oregon home after a search was conducted. A federal agent had made observations with an infrared camera outside of Kyllo's home which showed that there was an unusual amount of heat radiating from the roof and side walls of the home. (The assumption is, to grow indoors, one needs to provide lots of light so plants can photosynthesize.) This information was subsequently used to obtain a search warrant, where federal agents discovered over 100 marajuana plants growing in the home. Kyllo first tried to supress the evidence, then plead guilty. Kyllo appealed to the Ninth Circuit Court on the grounds that such observations with a thermal-imaging device constitutes a search under the Fourth Amendment. There, the conviction was upheld.

Opinion of the Supreme Court
The Supreme Court ruled 5-4 that the imaging of Kyllo's home constituted a search. Since the police did not have a warrant when they used the device, the search was presumptively unreasonable and therefore illegal.



Affidavit for warrant- Make sure there is no false facts, if so


II the evidence from a search based on the warrant may later be excluded upon the proper motion being e If the warrant is issued on the basis of statements in the affidavit that the police knew to be untrue or which were recklessly made without proper regard for their truth, the evidence from a search based on the warrant is not valid. By submitting a false affidavit, Officer Fox did not act "in good faith." The search was thus improper, and whatever it turned up is inadmissible in evidence.

At common law, all evidence, no matter how seized, could be admitted in court. In Weeks v. United States, 232 U.S. 383 (1914), however, the Supreme Court adopted the "exclusionary rule," whereby evidence seized unlawfully was declared inadmissible in court. The rule mainly serves as a deterrent to police officers seeking to conduct unlawful searches and seizures; it has, however, a number of exceptions. The rule was extended to the states in Mapp v. Ohio 367 U.S. 643 (1961). In United States v. Leon, 468 U.S. 897] (1984), the Supreme Court applied the "good faith" rule: evidence seized by officers objectively and in good faith relying on a warrant that was later found to be defective was still deemed admissible. If an officer dishonestly or recklessly prepares an affidavit forming the basis of the warrant, if the issuing magistrate abandons his neutrality or if the warrant lacks particularity, however, evidence seized pursuant to the warrant would still be excluded.

Despite their clarity, the Fourth Amendment's protections against "unreasonable searches and seizures" have in fact been drastically weakened since they became the law of the land in 1791. As it stands today, unless there exists a "reasonable" expectation of
privacy -- that is, a "reasonable" expectation that what one does or says will not be seen
or heard by someone else -- neither local police nor federal law enforcement authorities are required to get a warrant or other court order before they start a surveillance operation.