Exceptions to warrant requirement:
a. search incident to a lawful arrest: police may search the person and areas into which he might reach to obtain weapons or destroy evidence (“wingspan”; including the entire passenger compartment of a car); police may also make a protective sweep of the area if they believe accomplices may be present; search must be at same time and place of arrest; police may make an inventory search at the station of the arrestee’s belongings and may make an inventory search of impounded vehicle
b. automobile exception: if police have probable cause to believe that a vehicle contains fruits, instrumentalities, or evidence of crime, they may search the whole vehicle including the trunk and any container that might contain the item for which they had probable cause to search, no matter who owns it; car may be towed to station and searched later; if car itself is contraband police may seize it from a public place w/o a warrant; probable cause may arise after car is stopped but must be present before search; if probable cause is only for container recently placed in the car, may only search that container
c. plain view: police may make a warrantless seizure when they are legitimately on premises, discover evidence, fruits, or instrumentalities of crime or contraband, see such evidence in plain view, and have probable cause; plain view includes any place officer can legally look
d. consent: voluntary and intelligent consent waives warrant requirement; scope of search limited to scope of consent; if police claim to have warrant, that negates consent; police not required to tell you that you don’t have to consent; anyone with right to use property can consent
e. stop and frisk: police officer may stop a person without probable cause if he has a reasonable and articulable suspicion of criminal activity; if reasonably believes the person is armed, may conduct a protective frisk; frisk limited to pat down of outer clothing unless officer has specific information about location of a weapon; officer may reach into clothing and seize any item that officer reasonably believes, based on its plain feel from the outside, was a weapon or contraband
f. hot pursuit, emergencies, and evanescent evidence:  once police enter under hot pursuit, search can be unlimited; can enter any place in hot pursuit