Balkanization asks this question and highlights a paper prepared by the Texas District and County Attorney Association (one of our states' professional associations) regarding warrantless searches that suggest the search was probably illegal.
The article states:
Four circumstances must be present when officers enter a home, without consent or warrant, to search under these circumstances:
• the offender might escape if police do not make an immediate entry;
• the offender has demonstrated that he poses a danger to the community (for instance, the crime just committed is a crime of violence);
• the offender has been pursued into the house continuously from the crime scene; and
• the warrantless arrest would be lawful if accomplished in a public place but that cannot be done because of the suspect’s decision to retreat into a private place.
And Balkanization points out that one of these factors was not met in the search:
There was ample justification for the arrest of the suspect, there was little question that he posed a danger to the community, and there was a credible flight risk. Importantly, however, the suspect was not “pursued into the house continuously from the crime scene.” He was pursued into a large, general region of a city. Even in cases involving a single house, “[t]he information must be fairly specific … merely investigating a potential danger may not justify warrantless entry.” The lack of specificity here is only more pronounced; officers had no specific or articulable reason to believe that the suspect was present in any given house in the 20-block perimeter. In fact, the suspect was ultimately found by accident, and not by police but by a civilian, safely outside the 20-block area.
And what about the idea that the magnitude of the crime justifies the legality of the search? The author points out that Justice Scalia argued against that justification in an opinion issued last year:
Nor do the Fourth Amendment’s requirements evaporate due to the serious nature of the crime being investigated. “There is no precedent” for such a proposition, as Justice Antonin Scalia, writing for the Court, reaffirmed just last Term. And accepting such a “novelty” would lead to a cornucopia of “vexing problems”: in investigations involving “extraordinary offenses,” if it’s okay to conduct nonconsensual warrantless searches of every house in a 20-block area, what of searching every house in a 30-block area? Or a 100-block area? What exactly constitutes an “extraordinary offense”?
The article from the TDCAA makes a useful point about the desirability of warrants:
Without question, federal and state law contains a decided preference for warrants. The advantages of having a warrant are: 1) the officer or prosecutor drafting the affidavit can discuss the facts and craft a statement of probable cause with care; and 2) a magistrate reviews the information from the officer or prosecutor before deciding to issue the warrant. When a case involving a warrant goes to court, the presumption is that the seizure was lawful, and the burden is on the defendant to show the warrant was deficient.
Nonetheless, courts recognize that it is not always practical or desirable to ask an officer to stop what he’s doing to get a warrant, and for this reason, federal and state constitutional law recognize several exceptions to the rule requiring a warrant for any search.