Usually, there are four situations where San Diego police may search your person or property without obtaining a search warrant:

Consent. If you give police permission to search, they do not need a warrant.  However, it is best not to do this until you have spoken with your criminal defense attorney.

Incident to an Arrest. If you have been arrested, the police can search you as well as the immediate area where they arrested you (for example, your car or home) for any evidence or weapons.  If any evidence is found, it can be used against you.  In addition, if the police believe that there is an accomplice to the crime that may be hiding in your home, they can search the house and any evidence that is out in plain sight can be taken and used against you.