Constitution strictly limits the power of law enforcement officers to make searches. With a few very limited exceptions, you can conduct a search only if you have probable cause to believe that evidence of a crime is located in the place you wish to search. .
The probable-cause test for a search is similar to the probable-cause test for an arrest. It requires a reasonable belief, based on a reliable source, that contraband or evidence of a crime is in the place to be searched. It must go beyond mere suspicion or an educated hunch. On the other hand, probable cause is less than an absolute certainty. The evidence you need to conduct a search does not have to amount to proof of guilt. It must show that evidence or contraband is probably in the place to be searched. .
As a general rule, a search must be supported by a valid warrant. There are, however, limited exceptions to this rule. While these exceptions are important,you should keep in mind that in close cases, a search without a warrant may be upheld when a search without a warrant will be declared invalid. Moreover, obtaining a warrant whenever possible forces you to review your case and may reveal significant flaws in the evidence that can be corrected before the case is botched. .
The major exceptions to the warrant requirement are the following: searches "incident to" a valid arrest; automobile searches made under certain conditions; searches made under emergency conditions or exigent circumstances; and searches made with valid consent. .
Search incident to arrest means at the time you make an arrest, or immediately after the arrest, you may search the arrested person and the immediate area into which he or she can reach. If the arrest takes place in or near an automobile, you may, incident to arrest, search the passenger compartment and any containers you find inside. You can make a warrantless search of a car which was in motion, or at least mobile, when seized, and which you have probable cause to believe contains contraband or evidence of a crime.