I'd say it'd depend on context, Clapee. If there were exigent circumstances that precluded authorities from obtaining a warrant in a timely fashion, then I'd agree that a warrant wouldn't be required. But that wasn't the case in this instance - the DEA had ample time to obtain a warrant based on the surveillance evidence obtained from their informant. That they consciously chose not to avail themselves of this option (thinking, no doubt, it better to ask for forgiveness than permission), in my opinion, constitutes a clear violation of Mr. Huskisson's 4th Amendment rights.
I mentioned the Gates case as an illustrative example of the steady erosion of the 4th Amendment's protections by the Courts since the early 1980's. Prior to Gates, the standard was the Aguilar-Spinelli test wherein an informant's credibility and reliability in addition to some of the circumstances involved in obtaining their information are pivotal considerations when deciding on probable cause. The Gates decision swept that away... now anonymous tips and "totality of evidence" are all that is required. So where is the 4th Amendment safeguard against "unreasonable search & seizure" in the post-Gates world? Anyone can give the police an anonymous tip for any reason..... could be an authentic informant with legitimate information, could be someone with an axe to grind... hell, could even be the police themselves looking to "shake things up"! So, I ask you.... what was so constitutionally flawed about Aguilar-Spinelli that it had to be abandoned by judicial fiat with Gates? If having the Supreme Court decide that the 4th Amendment's protections are to be taken so lightly that they can be pushed aside by an anonymous tip of unknown, unproven and unverifiable credibility isn't an example of clear jusidicial activism, then, what, I ask you is it?