In order to prove guilt in a case of alleged driving while intoxicated (DWI) in New Jersey, the state must be able to justify all of the police’s actions leading to the DWI charges. This includes the officer’s decision to stop the defendant’s vehicle, the basis for conducting an investigation, and the decision to place the defendant under arrest. The Fourth Amendment to the U.S. Constitution generally prohibits warrantless searches and seizures, although numerous exceptions apply. Courts have held that evidence in a police officer’s “plain view” may justify a warrantless search. Similarly, odors that are within an officer’s “plain smell,” such as the smell of alcohol emanating from a vehicle, may serve as a basis for suspecting a driver of DWI.
The “plain view doctrine” holds that police may conduct a limited search without a warrant if contraband or other evidence of unlawful activity is plainly visible to them. For example, if an officer pulls a car over for speeding, and they can see a bag of drugs sitting in the passenger seat, they may be able to search part or all of the vehicle without a warrant. The “plain smell doctrine” gives police a limited right to conduct a warrantless search based on odors that suggest illegal conduct. This often involves the odor of alcohol or marijuana. A 2018 ruling by the New Jersey Appellate Division held that merely smelling something is not a “search” within the meaning of the Fourth Amendment. “[A]n officer standing outside of an automobile who smells the odor of marijuana emanating from within it” the court held, “has not conducted a ‘search.’”
An officer’s testimony about smell might not be enough, by itself, to justify an investigation or arrest. Police rarely stop a vehicle because of an alleged odor of alcohol, if only because smelling a moving vehicle is exceedingly difficult. Police must be able to justify the traffic stop before odor-related evidence is even a factor. In a 2019 ruling, the Appellate Division considered a defendant’s challenge to the arresting officer’s request to conduct field sobriety tests. The court recounted the officer’s testimony about the defendant’s driving, which reportedly included weaving and a “California stop,” provided reasonable suspicion for the stop. At that point, the defendant’s appearance, along with the smell of alcohol, provided probable cause for a DWI investigation.