Generally, an officer can search your person, car, or home with a warrant. If you are suspected of a crime such as drug manufacturing or selling illegal weapons, a police officer can present evidence to a magistrate to obtain a warrant.
There are a few instances, however, where police can search your property and possessions without a warrant. In Georgia, the trained perception of the odor of burning marijuana is sufficient probable cause to support a warrantless search of a car. Folk v. State, 191 Ga. App. 58 (1989)
Consenting to a Search: Law enforcement can search your possessions and your vehicle if you consent to a search. If a police officer is asking to look through your things or your property, you have the right to refuse. It’s best to respectfully decline with clear language such as “no, officer. I do not consent to searches.”
Plain View: If you have suspicious items, weapons, or drug contraband/paraphernalia in plain view, an officer can search your possessions and your car without a warrant or your consent.
Stop and Frisk: While the concept of stop and frisk has been contested in places like New York City, there was a Supreme Court case (Terry v. Ohio) that upheld a law enforcement officer’s right to pat down suspects of crimes. While these pat downs are normally exercised to ensure that a person isn’t armed, officers can confiscate contraband such as illegal substances if they are found.
DUI Checkpoints: A Supreme Court ruling (Michigan v. Sitz) found that DUI checkpoints where officers stop drivers to check their license, insurance, and registration are permissible. It is also permissible to administer field sobriety tests and breathalyzers at these checkpoints, too if an officer smells alcohol or marijuana or if empty bottles or drug contraband are in plain view.