Ok, fair enough, for the sake of the discussion, from the sidewalk it is not a search. It would be perfectly legal and reasonable for the police to command the dog on the sidewalk to “smell” and then let the dog indicate that whatever contraband it smelled was coming from the house.
Ok. Next step. Do you think it’s a search if the officer, without a dog, comes up to your door to knock and ask some questions and smell whatever odors might waft out?
Nope
No, you don’t get to separate the two. What constitutes a legal search on public property is not the same as what constitutes a search on private property. If a police officer finds a desk on the side of a road, a search warrant isn’t needed to open desk drawers to look for information and/or items. If that same desk happens to be in my home office four hours prior, that same officer better have a search warrant to conduct a legal search of my property on my property.
The part that Bricker left out is that the officer needs reasonable suspicion to make the traffic stop in the first place (which means some articulable basis beyond his prime number theory or whatever). In the case we are discussing, the officer has reasonable suspicion, although he doesn’t need it just to walk up to the house.
Ok Cheesesteak. Now suppose the officer brings the dog, and while the dog is capable of doing a contraband sniff, he doesn’t do so. A search?
I’m not trying to separate anything. I’m trying to isolate the facts that you think are legally dispositive and examine them more closely. It’s different.
Still not a search
What if the desk is in your front yard? That seems a more apt analogy here.
Clarification, please: does this hypothetical dog decide on its own whether to sniff a place out, or doe it respond on command?
Now suppose the dog sniffs the inside, but doesn’t alert or otherwise react in any way. The officer leaves. Was it a search?
Ah, now you see how we isolate important facts! 
Does it matter which it is? Let’s say on command for present purposes, but it might be interesting to see how you come out on the other version eventually.
Without anyone’s knowledge, the instrument turned itself on, but didn’t give a readout to the officer? Are you asking whether the cat in the box is alive or dead?
boy, you’re really cutting it fine now.
I’ll still say no, assuming that the dog was not directed to sniff by the officer, or trained to sniff without reacting by officers.
You’re missing the point. The officer is not allowed to detect legal activity unless he either has permission to perform a search or he’s only using ordinary methods available to everyone - that is your right to privacy. It doesn’t matter what he does with it or what he’s looking for, it’s an illegal search.
Do I correctly infer that if the officer commanded the sniff, but it is otherwise the same scenario (i.e., the dog sniffs but doesn’t react), that you believe it to be a search?
The officer took the equipment that can no way on earth be described as “his nose” to the front door and turned it on to detect the contents therein? Search.
The other scenario: The officer took an instrument that is always on up to the front door to detect the contents therein? Search.
That’s a fine assertion, but it’s not an argument. I’ve already explained to you (actually Stevens had explained) why *Kyllo *does not so hold.
Ok. This is very helpful.
Same facts, but the dog actually has no sense of smell (but the officer doesn’t know this). Still a search?
(I know this seems fanciful, but this is to test whether it’s the intent of the officer that you think is key.)
If the officer commanded the dog to sniff, or the dog was trained to sniff, I would think there would be a purpose to that. He is no longer a passive participant in this scenario, he’s been activated, and is gathering information about what is inside my house. The fact that he is not reacting does not mean he won’t react in the future, after a command to do so.