Dolly Mapp was a formidable woman. When the cops of Cleveland Ohio arrived at her door, in the early 1960’s or thereabouts, seeking a person in her house, she declined to allow them entry. They called in reinforcements (what a woman!). They searched her house and found pornographic material. She was convicted, lost on appeal and won in the US Supreme court [Mapp v Ohio 367 US 643; S.Ct. 1684]. The cops had searched without a warrant. Dolly had been convicted under the law of Ohio. The US constitution [14th Amendment] protected a citizen from unreasonable search and seizure and in 1914 the US Supreme court had ruled evidence obtained in breach of the constitution could not be relied on in a Federal prosecution. Mapp v Ohio decided that that position also applied to State prosecutions. (Most criminal prosecutions were under State law, so most defendants had been left without the protection of the constitution until Mapp).
In or about 1986, on a tip-off, police in California flew an aeroplane over the backyard of Mr. Ciraolo. They perceived a crop of marijuana in his yard, got a search warrant and found 73 plants. The California court of appeals applied Katz v United States 389 U.S. 347 and ruled the flight an unauthorised search and a breach of Mr. Ciraolo’s expectation of privacy. The US Supreme court found against Ciraolo on the grounds that he had lost his right of expectation of privacy because he had exposed the back yard to the occupants of the numerous aeroplanes flying over his house. The court disregarded the fact that those occupants were passengers in domestic flights (at great heights, presumably) whose chances of inspecting and recognising marijuana in the backyard were nil.
One wonders what the US court will say when the cops buy and deploy drone aircraft and thermal imaging technology.
Then there are those special places like Birr, County Offaly where, recently, the 41st Irish Hot-Air Balloon competition took place. Will the Garda Síochána buy a balloon or opt for a drone?
The Gardaí have had a history of their own difficulties with search warrants and the like. See HERE for the latest episode on that front and for a very good analysis of the case law relating to that history.