Does the officer have to see me driving badly to arrest me for DUI?

No. Plenty of arrests begin with something unrelated to driving — an equipment violation, a crash nobody witnessed, a welfare check on a parked car, a stop for a suspended tag.

But the absence of a driving pattern matters more than people realize. Prosecutors value that evidence because it's independent — it exists before any interaction and before any judgment call. Without it, the case reduces to what one officer smelled, saw, and concluded during a few minutes on the roadside.

Juries notice the difference. A person driving normally, stopped only for a tag light, who then showed clues on a dark shoulder presents differently than someone weaving across three lanes.

There's a related point in crash cases: if nobody observed the driving, the State also has to prove the person was the driver at all.