There are numerous ways that the readings can be excluded from evidence ranging from illegal stop by police, illegal search issues, improper use of a breathalyzer instrument, improper timing of the breath tests to the taking a video of an accused urinating behind the doors of the bathroom facilities. There are far too many possible issues to list but the answer to the question is that it is possible to win even if you blew over 80 and again each case turns on its own facts.