Question: How accurate is the preliminary breath test in Maryland and am I required to take it?
Answer: No, you’re not required to take the preliminary breath test. You can refuse it. Police officers, some of them will tell you that, others will not—they will just whip it out and say blow in this device, and then people tend to do that. As far as how accurate it is, you can’t really say because they aren’t calibrated and they aren’t maintained under strict standards like the real breath test at the police station.
Those are maintained on a monthly or multi-monthly basis, whereas the PBT test, as it’s known, preliminary breath test, PBT, is not. It’s just a device that rides around in the officer’s trunk until he feels like using it. Most important thing is that number is not usable by the police officer in court, which is nice. They can’t use it against you, but it certainly gives the police officer probable cause, so if you blow into a device and it’s not necessarily reliable and you register as a .08 or a .09 or a .10, the officer is then going to say, “I have probable cause; I’m now going to arrest this person and take them to the police station and require that they blow.”
If this little PBT were to register .03, or a .04 or .05, the officer may or may not arrest you. So whether or not that machine is reliable remains somewhat important because it has to do with, at least in part, whether a person will be arrested. But, then the final analysis, the machine is not deemed to be reliable and by the courts, and that number does not come into evidence, unless the defendant wants to use it. If the number helps the defendant, because you blew a .05, and the defendant feels like he wants to use that number in court, then he can do that. But, the police cannot.