In any criminal case where the police searched for and seized physical evidence of any kind, one of the first things we examine is the question of whether the police had a valid search warrant and/or whether a search warrant was necessary. In most contexts, the police need to obtain a search warrant from an independent judge or magistrate prior to being legally allowed to search for evidence. However, there are some exceptions to the search warrant requirement. This commentary considers a few of those exceptions – if these exceptions are absent, then good ground probably exists to file a Motion to Suppress the use of the evidence at trial.
Consent – Anytime a party gives consent to search, the please may search the area, even if they do not have probable cause. Note that the person giving consent must have the proper authority, or at least appear to have the authority, to give consent to search the area, i.e., my neighbor can't give the police permission to search my house.
Plain view – The police are permitted to seize contraband or any evidence of a crime when the evidence is in the "plain view" of the police officer at the time of the seizure. Note that the officer must be lawfully present in an area in order for the plain view exception to work.
Automobile searches – because automobiles can be easily driven away from a scene if there is a delay, law enforcement officers are permitted to search automobiles under any circumstance in which they have probable cause to believe that the automobile contains contraband or evidence of a crime.
Exigent circumstances – The police are entitled to search certain things and areas under the "exigent circumstances" doctrine. Exigent circumstances is essentially a legal term for "emergency," and police officers are entitled to search any place they are present as the result of an emergency – even a home if their entry into the home is based on exigent circumstances. The emergency might be a personal emergency, i.e., someone has called 911 and the police can't get the person to answer the door. Or, the emergency might relate to destruction of the evidence. For example, if the police see somebody run into the house with a package of drugs, they can legally follow that person into the house – the emergency being the danger of the evidence being destroyed or taken away prior to the acquisition of a proper search warrant.
The stop and frisk search – Any time the police have legitimately temporarily detained a person to speak with them, including for a run of the mill traffic stop, the police may frisk the person to ensure that the person is not caring a weapon. If the police feel any object on the person's body that could be a weapon, even if the object turns out to be something different, they are entitled to search that area.
There are many other instances where law enforcement officers are permitted to conduct searches and seizures without search warrant, but the above circumstances present the most common exceptions.