Can the police enter without warrant (or statutory or common law authority) the house of an absent occupier to search for weapons that the absentee might use to commit suicide?
The Supreme Court of the United States has held, no: Caniglia v Strom, 20-157 USSC May 17, 2021.
The Court was unanimous, and was careful to make it clear that this decision did not affect the established law relating to entry without warrant but in exigent circumstances. The exigent circumstances exception has been confined within narrow limits, essentially so that the law conforms with common sense.
Broadly, it is not necessarily unlawful, in exigent circumstances - that is, circumstances of emergency to protect life - for the police to enter private property without first applying for a warrant to authorise that entry.
Independent of exigent circumstances, the police may (in the United States at least) generally take actions that any private citizen might take.
This decision of the Court rejects the proposition that the police may act pursuant to a “community caretaking” duty.
So, caretaking is insufficient to make warrantless entry of private property lawful; there must be exigency.
Recognition that the police can do what any private citizen might lawfully do, is controversial. It calls to mind the “third source” of governmental authority proposed by some jurists. See, for example, BV Harris, “A Call to Maintain and Evolve the Third Source of Authority for Government Action” (2017) 27 New Zealand Universities Law Review 853. See also my comment on Ngan.
The "third source" theory, repeated almost to the point of reifying the concept, is that sources of legal authority - here, the authority of the police as exercisers of the executive power of law enforcement - are legislation, firstly primary, or secondly delegated (regulations or legislative instruments), or "thirdly" facts which call for a response. [1]
Regardless of its source, a power of search must be exercised reasonably. Reasonableness (or, absence of unreasonableness) is not the source of the power, but it is descriptive of how the power must be exercised to continue to deserve recognition as lawful.
Unlawful searches are unreasonable (there are very narrow exceptions to this - for example, where the police in good faith endeavoured to comply with a law that was open to various interpretations and which needed clarification by the legislature or by the courts), and lawful searches are sometimes carried out unreasonably.
We might doubt whether a third source is needed in the context of cases like Caniglia v Strom. The courts can craft rules about police entry into residential property if elaboration of the requirement of reasonableness is required. But the source of lawful authority is primary or secondary legislation. To place the source of legality in the facts of a case is to invite anarchy. [2]
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[1] I am differing here from the usual counting of sources, in discussions of governmental powers, where the first two are parliamentary and the royal prerogative. In the present context it seems sensible to recognise the two types of legislation, as the prerogative has no application to the law of search. It may be suggested that the third source is really that which is necessarily implied with the grant by legislation of search powers. But implications are not necessarily obvious without a factual context, and where that is so I prefer - for third source purposes - to think of the facts as giving rise to (in the sense of motivating) the interpretation. Implications from the text of legislation are first or second source, whereas implications from the facts might be third source - if indeed the third source is a real thing. See S v Commissioner of Police [2021] NZHC 743 at [64], [80].
[2] Just a bit of exaggeration here, probably. The name "third source" may be misleading: it seems to be not a source of power but a freedom that exists to do what is not prohibited by positive (legislation or judicially-made) law. See Jeff Simpson, "The Third Source of Authority for Government Action Misconceived" (2012) Auckland University Law Review 86. While we are thinking about this, and the hypothesised power of the police to do anything that an ordinary person could lawfully do, let's note the Right Honourable Sir Stephen Sedley's comment in London Review of Books, vol 43, no 13 (1 July 2021), p 19: (in an only slightly different context), that is "a formula that embraces acting out of caprice, greed or spite."
