Rising Alcohol Defense
The rising alcohol defense is an interesting and complicated concept which happily does not apply in the state of Maryland. Maryland is considered a time of test state versus a time of driving state. Maryland's law is written that the BAC is to be considered at the time of testing while other states may consider the BAC at the time the defendant was driving their car despite the fact that the test is generally taken one to two hours after a person is arrested.
So in Maryland it is a requirement that a breath alcohol test must be obtained within two hours of the arrest in order for it to be used against the defendant in court. The law assumes that a test taken within two hours of an arrest will be close enough to the person's actual BAC at the time of their driving in order to properly convict them of the charge of impaired driving. This of course is a fallacy and is only tangentially relevant when a test is obtained close to two hours after being arrested. Happily, most be BAC tests are obtained within roughly one hour of driving the car So they are probably fairly close to the BAC at the time of driving.
Rising and falling alcohol can certainly be a factor in a test which is obtained 1 to 2 hours after an arrest but the state of Maryland does not put any creed on that when they write their statute to indicate the BAC at the time of testing. By way of explanation, the rising and falling alcohol should be important because it takes time for alcohol to be absorbed into the bloodstream through the stomach and small intestines after it is consumed particularly if there was the consumption of food at the same time. Thus if a person had dinner and drank wine with their dinner and then left the restaurant and drove home and was stopped for speeding, is very likely that the person may not have been impaired in any way or certainly under a .08 at the time driving but when a test is offered one to two hours later the driver's BAC may be much higher as the alcohol was subsequently absorbed into the bloodstream.
It can also work the other way in terms of consuming alcohol at a bar and then leaving and being pulled over for whatever reason. 1 to 2 hours later a number could fall under .08 or if it was .15 at the time of arrest it could fall underneath that high threshold number which may prove beneficial to the defendant at a subsequent MVA hearing. Consequently in Maryland, some things are made easier as the rising alcohol defense is not a viable defense and that rules out such scientific quagmires as retrograde extrapolation. However, because we use the "time of testing" as the effective number this is both easier to prove on the government and perhaps less accurate for the defendant when it comes to what is BAC truly was at the time of the operation of his motor vehicle.