What proof is needed in an OUI prosecution?

Like other criminal prosecutions, the Commonwealth bears the burden of proof and defendants do not have to prove their innocence. Even before an OUI defense is presented, the Commonwealth must prove its prosecution case beyond a reasonable doubt.

The Boston prosecution does not have to prove that the driver was drunk. The Commonwealth must prove, beyond a reasonable doubt, that the defendant drove a vehicle on a public way or a road where the public has the right of access while they were under the influence of an intoxicating liquor. Or, it must prove that they drove the vehicle while their blood level was at least .08 percent regardless of any evidence of impairment.

A driver is under the influence if alcohol lowered their alertness, judgment and ability to promptly respond. This includes a drunk driver. It also includes any motorist who consumed enough alcohol to reduce their ability to drive safely by lowering their mental lucidity, self-control and reflexes. The amount of alcohol that lowers driving ability varies among individuals.

Proving that a driver was under the influence does not require proof that the motorist was actually driving in an unsafe or unpredictable manner. Proof must demonstrate that alcohol lowered the motorist’s ability or capacity to operate their vehicle safely.

Cases usually concentrate on whether the accused driver was under the influence and had the capacity to drive safely. If there was a blood or breath test, its accuracy is important for a successful prosecution.

A blood or breath test of at least 0.08 percent may be sufficient proof for an OUI conviction even if the evidence shows that the motorist was not displaying any signs of impairment. Proof that the motorist was driving on a public way or operating a vehicle are usually not issue because these facts are rarely contested.

A motorist accused of operating under the influence should seek immediate legal representation. An attorney can challenge evidence that was illegally seized, tests that are invalid or any other evidence that should not support the Commonwealth’s case.