Can a witness at trial give the opinion that you are too drunk to drive?

At a trial for operating under the influence of alcohol, there’s some confusion among the average citizen as to what a witness can and cannot say at trial regarding the level of someone’s sobriety.  The courts have consistently held that a layperson can testify as to how someone behaved and whether they seemed “drunk.”  What confuses people is that there is a distinction between being “drunk” and the legal issue at trial, which is whether the person was impaired so much that it diminished their ability to operate a motor vehicle safety.  The legal issue is the issue for the trier of fact at the trial, which can be a jury or the judge, depending on whether the person charged picked a jury trial or a bench trial (no jury).  Even a police officer is not allowed to opine that the person was so impaired that the concluded beyond a reasonable doubt that they could not operated their motor vehicle safely, even though the officer can say “he/she was probably impaired.”

One of the more recent and most often cited cases regarding this issue is Commonwealth v. Canty, 466 Mass. 535 (2013).  In Canty, a police officer was parked monitoring traffic when he saw a vehicle coming in his direction nearly strike the curb.  He followed the car for three-quarters of a mile and saw it drift over the fog line and back across the double yellow line.  The officer turned on his blue lights but the car didn’t stop until about 20 seconds later, when it pulled to the side of the road.  When the car pulled over, the reverse lights were still on, and the operator didn’t know how to put it in park, it appeared.  The officer exited the car and spoke with the operator who stated that it wasn’t his car.  The operator had trouble getting his license and registration to give to the officer, and the officer smelled an odor of an alcoholic beverage on his breath.  The operator’s eyes were bloodshot and he admitted to drinking four beers over four hours, about two hours earlier.

The officer asked the operator to get out of the car and perform some field sobriety tests.  This is a good opportunity to point out that you are NOT required to perform field sobriety tests. You can refuse.  Although, you will probably get arrested anyway, but at least there won’t be any field sobriety tests to critique and a jury will never hear you refused field sobriety tests. The operator here performed poorly on the tests and was arrested as a result.  A half of a bottle of brandy was found in the car. 

Before trial, the counsel for the defendant moved to have any opinion by the officer as to whether the defendant was “intoxicated, impaired, or under the influence of alcohol” excluded from testimony.  He argued that the issue was one for the jury, as it was the ultimate issue in the case.  The judge ruled that case law since basically the beginning of time as held a lay-witness can testify to someone’s level of sobriety.   The officers testimony ended up stating “I believe his ability to drive was diminished…I believe it was alcohol consumption (the cause).”   A second officer testified “He was probably impaired.”  Because sobriety is an every day experience, and one which “the principal objective symptoms are so well known,” the court noted the lay witness opinion did have value.  However here, the issue is not sobriety, the issue whether the defendant’s ability to operate a motor vehicle safely was diminished.  And that is an ultimate issue that a jury must decide, and a witness cannot offer that conclusion.  The court has ruled in the past that letting a witness essentially tell the jury how a case should be decided basically “denigrates” the role of the jury.  So because a witness opinion like in this case basically offers their opinion on the guilt or innocence of someone, it is not admissible.

The Court’s ruling was : “The balance we reach is that a lay witness in a case charging operation of a motor vehicle while under the influence of alcohol may offer his opinion regarding a defendant's level of sobriety or intoxication but may not opine whether a defendant operated a motor vehicle while under the influence of alcohol or whether the defendant's consumption of alcohol diminished his ability to operate a motor vehicle safely.”

Unfortunately for the defendant in this case, the ruling mattered little, because the court also noted that the evidence of impairment was overwhelming to the extent that the testimony swayed the jury, and a rational person could still find the defendant guilty without the opinion of the officer.