Reasonable suspicion

[HighwayMan]

Okay ... "the odor of an alcoholic beverage emanating from his person ..." ... <grumble, grumble ... smart aleck ...>

Sorry I couldn't resist. When it comes to stuff like that I hold you to a higher standard than the rest of the crew here.

But, the reasonable suspicion to support the stop was not a mystical feeling the driver may be impaired, but some observed driving (or equipment failure) ...

Which may or may not be something indepedently chargeable.

But, the weave is the RS that might lead to a DUI, and the stop would be made for the weaving, not for DUI.

Yes, but the weave (legal) could be a sign of something else going on which is not legal. The two main ones are use of a portable electronic device and DWI/DWAI. Generally, the former would be brief and continuing over a relatively short time period. The latter would be more pronounced and consistently observed over time.

Not being argumentative, just pointing out that there are stops made for suspected DWI - yes, based upon observable behaviors which may or may not be illegal in and of themselves.