During a recent OVI jury trial, the judge and I disagreed about the function of standardized field sobriety tests (SFSTs). During a sidebar, I argued the tests do not measure driving impairment; they predict blood alcohol concentration (BAC). The judge’s opinion was SFSTs measure impairment of driving ability. The judge’s opinion prevailed, despite being wrong, because the judge’s opinion always prevails in the judge’s courtroom (unless and until an appellate court says otherwise). This particular judge is intelligent, well-intentioned, and better educated on DUI/OVI issues than most judges and lawyers. If this judge misunderstands the purpose of SFSTs, it’s a topic worth addressing.