Testing saliva, breath, urine or blood are all ways to measure the amount of alcohol in your body. When you are stopped on suspicion of a DUI it is normal for them to give you the test right then. It is true that testing the blood is a sure way to measure the BAC, but the most common test and the one most used, as evidence is the Breathalyzer.

Many people use the terms Breathalyzer and BAC interchangeably, but there is a difference. A Breathalyzer does not read the actual alcohol content but it tries to estimate the level by testing the breath from your lungs to measure the amount of alcohol. What this means is that the Breathalyzer tests are far from 100% certain and may often be challenged. Although some states use urine or breath tests, the blood test gives the most accurate BAC level. There are some substances that will throw the results off when using a Breathalyzer machine. For instance, sometimes Acetone throws off the results of a Breathalyzer test, as it may show up in large amounts in someone on a special diet or if they have diabetes. There have been times that fumes coming from adhesives or paints have also confused them.

A blood test is the accurate way to determine the Blood Alcohol Content. But, there a few general rules that may help you estimate your level based on how much you drank and how much you weigh. In order to reach the .08% a 170 lb. man on an empty stomach would have to drink more than four drinks in one hour. And a woman weighing 135 lb. would need approximately three drinks in an hour to reach that same .08%.

Keep in mind that if you get pulled over for suspicion of DUI by a law enforcement official it is normal for them to give you a Breathalyzer test. If you refuse, in most states that results in an automatic suspension of your license. It may even bring additional criminal or civil sanctions and is normally used as evidence against you.

The 2 tiers are:

1. Driving under the influence (DUI)

(BAC ≥.08; called “A” offenses)

Maryland has administrative per se with license suspension for BAC ≥.08. Offenders have the right to a hearing before an Administrative Law Judge (ALJ). The ALJ can dismiss the suspension or can modify the suspension to allow driving to work, school, alcohol treatment, or other purposes.

2. Driving while impaired (DWI)

(BAC <.08; called “B” offenses).

Maryland allows Probation Before Judgment (PBJ), under which offenders may be given one year of probation with alcohol education; upon successful completion the driver’s record is cleared so there is no record of a prior alcohol offense.

Test refusal results in administrative license suspension for 120 days for first-time offenders and 1 year for repeat offenders, which again can be appealed to an ALJ. Driving to work or other purposes may be allowed under the condition that the driver uses an alcohol interlock. Test refusal suspensions are in addition to any criminal penalties that may be applied.

Penalties increase for repeat offenders (defined as a second or subsequent offense within 5 years) and for drivers transporting a minor. Penalties are not increased for drivers with high BAC levels — Maryland does not have a high-BAC aggravated DWI law.

The tables below summarize the  penalties involved. The only “mandatory” minimum penalty is 5 days in jail or 30 days community service for a second “A” offense within 5 years.

Maryland Administrative Driver’s License Sanctions

Maryland Criminal Penalties

Source: National Highway Traffic Safety Administration