Now extend that thinking to traffic stops and searching an automobile. Wouldn't a warrant be necessary to search a vehicle since it is private property? If a traffic stop is for speeding then does that automatically give the officer the right power to search a person's auto? Shouldn't the driver simply be cited for the offense for which they've been stopped and then released? (always ask the officer why you have been stopped!)
Now, I'll concede that if an officer smells alcohol on the driver's breath while talking to them, if the driver acts and /or responds in a deceptive manner or a Cheech and Chong style fog of marijuana smoke comes out of the vehicle when the window is rolled down, they then have probable cause to search a vehicle, so let nobody say I'm being unreasonable or "against" law enforcement. If there is probable cause then there are inherent powers. If a man has long hair he shouldn't automatically become a druggie, nor if the driver is a black man should he automatically be a thief in the eyes of the officer. And an automatic power to search the auto just because the officer doesn't like the look of a man is simply wrong.
And there is also the random checkpoint aspect where drivers are being stopped, questioned and their vehicles are searched for no reason whatsoever other than they happen to be on the road where the checkpoint has been established. It seems to me that the checkpoints are little more than fishing expeditions. Drivers do nothing wrong yet they are subject to questioning and having their private property searched, all without suspicion, probable cause or, most importantly, a warrant.
The checkpoints are only allowed to check for driver's licenses, valid tags, and insurance cards. The police can NOT search your car without probable cause - while the cloud of dope smoke will net you an immediate arrest and search incident to arrest, for the alcohol they have to get you out and run the field sobriety tests and the alco-sensor and arrest you. And they can't do an impound search on your car unless there's nobody who can drive it home.
Otherwise, they can question you if they have an 'articulable suspicion' - called a "Terry stop" after Terry v. Ohio. The questioning must develop probable cause, or they must ask for and receive permission to search.
As for a speeding stop, once the officer has written the ticket and checked the radio for outstanding warrants, he may not 'unreasonably prolong' the stop to ask intrusive questions about other matters, to wait for a drug-sniffing dog, etc.