Lack of probable cause in a simple traffic stop. It would be like the cops being called for a noisy party, they arrive and it is not noisy at all, but they go ahead and search the house while they are there.
And SCOTUS can be quite schizo in that regard. In Kyllo v. United States they found thermal scans of a house - used to look for pot growing - to be unconsitutional. How is a thermal scan of a house different from a dog sniffing a car from the outside? Same intent, same lack of due cause, similar concept of remote sensing.
The SCOTUS matter was when I was called for federal jury duty. I vehemently disagreed with a recent SCOTUS decision that would have had bearing on the case in question. I voiced my disagreement in sidebar. And five years later, SCOTUS effectively reversed that decision. It's not that I had any direct bearing. But I can smell unconstitutional actions a mile off, even if SCOTUS sometimes cannot.
“It would be like the cops being called for a noisy party, they arrive and it is not noisy at all, but they go ahead and search the house while they are there.”
Actually, it would be more like being called for a noisy party, and noticing a couple smoking joints on the front lawn...