Laws which state that if a specified level of alcohol is present in a driver's blood, the driver is presumed to have been driving under the influence or intoxicated. However, because the presumption is rebuttable, other evidence can be introduced by the defendant to disprove the allegation. This is where the Per Se violation comes into play.  If a driver is found to have a .08 or higher BAC, then there is a rebuttable presumption that the driver was driving "under the influence" of alcohol.  This number however has no relationship to whether the driver was actually under the influence at the time of driving, rather the mere fact that she blew that number on the test is enough to convict her of the charge (assuming the test was administered correctly and was otherwise a valid test).  Naturally, the latter is a point of contention in DUI cases in Maryland.