The Massachusetts Supreme Judicial Court has decided that a jury should not be given a specific instruction regarding the absence of a breathalyzer test or other alcohol-test evidence in an OUI case unless the defendant requests the instruction.
In a criminal trial, a defendant's refusal to submit to a breathalyzer test is generally excluded from evidence. In other words, it is improper for a jury to hear or even consider the fact that a defendant refused the test. This exclusion is based on a defendant's inherent right against self-incrimination; a defendant is not obligated to provide evidence against themselves by submitting to a breathalyzer test. If a jury were to learn that a defendant refused one of these tests, it could provide evidence that the defendant believed that their test result would be incriminating.
In Massachusetts, where there is no evidence of a breathalyzer test or other alcohol related tests, a judge might give the following jury instruction:
"You are not to mention or consider in anyway whatsoever, either for or against either side, that there is no evidence of a breathalyzer (or other alcohol-test evidence). Do no consider that in any way. Do not mention it. And put it completely out of your mind."
It was acknowledged by the Court that this instruction does quite the opposite of what was intended -- it focuses a juror's attention on the missing evidence. Further, it mentions evidence that was not introduced at trial based on a defendant's right against self-incrimination. While we assume jurors will follow the instructions provided by the judge, there are psychological issues at play that could cause a juror to improperly speculate as to why a particular test was not introduced.
In deciding to err on the side of caution, the Court held that giving this jury instruction is improper unless requested by the defendant.