What might constitute an exigent circumstance allowing for a warrantless search?

An exigent circumstance refers to a situation that creates an urgent need for law enforcement to act without a warrant due to immediate risks or threats. Observation of an ongoing crime is a classic example of such a circumstance. When officers witness a crime in progress, they may reasonably believe that waiting to obtain a warrant could allow for the destruction of evidence, escape of a suspect, or further victimization. Thus, the immediacy and direct observation of unlawful activity present a compelling justification for proceeding without a warrant.

The other choices fail to meet the standards for exigent circumstances. A tip from an anonymous source may lack sufficient reliability or urgency to justify bypassing the warrant requirement. Permission granted by a suspect does not fall under exigent circumstances; rather, it involves consent, which is a different basis for conducting a search. Following a traffic violation does not, by itself, create an immediate need necessitating a warrantless search, as it typically allows officers time to secure a warrant if needed.