Whether a person is acting nervous really has nothing to do with this.
A dog sniff for drugs isn't even considered a search.
Official conduct that does not compromise any legitimate interest in privacy is not a search subject to the Fourth Amendment. We have held that any interest in possessing contraband cannot be deemed legitimate, and thus, governmental conduct that only reveals the possession of contraband compromises no legitimate privacy interest. This is because the expectation that certain facts will not come to the attention of the authorities is not the same as an interest in privacy that society is prepared to consider reasonable.Essentially, if in the normal course of a legitimate traffic stop there happens to be drug-sniffing dog on the scene, the dog can sniff around the vehicle regardless of whether the driver seems suspicious. If it ain't considered a search, no reasonable suspicion is necessary unless the cop tries to keep you detained after he's finished checking your tag and your license and writing your ticket and whatnot.
[quote marks and citations omitted]
You may or may not like the line of cases, but this is really no change -- not even an extension -- from past cases.
As was noted a few posts up, the Supreme Court DID make a big change a few years back when they said you could NOT use outside heat detectors (thermal imaging), which had been common practice for a while