Under 21 Driver stopped for Speeding and Failure to Signal Turn. Shift commander hands over investigation to 2nd patrolman that conducts field sobriety tests. Driver completes tests with little difficulty but he is .09 BrAc on a Preliminary/Portable Breath (PBT). Following arrest driver submits to a Draeger Alcotest 9510 breath test with .09 result. At trial the prosecution cannot admit this post arrest breath test evidence. The PBT evidence in not admissible in Massachusetts. Not guilty finding following trial.