This is the subject of continuing debate among the defense bar which has become more complicated since Massachusetts adopted laws requiring a "guilty" finding upon a breathalyzer reading of .08 of higher and "Melanie's Law" in October of 2005. Many used to advise to never take the breathalyzer.  Others said doing so was fine if you have had one or two drinks.  Bear in mind the following generalizations: one 12-ounce beer equals 1.25 ounces of hard liquor equals one four-ounce serving of wine.  One’s blood alcohol level generally increases .02 percent for each serving.  Over an hour, your body clears the alcohol, through metabolism and excretion, at a typical rate of .015 percent for males; (the rate for women is 1.25 times greater).  However, many factors - e.g., what you had to eat, your basic body makeup, height, weight, state of health - affect the rate of alcoholic elimination.

Many experts believe that breathalyzers are inherently incapable of properly discerning one’s true alcohol blood level. 

Nevertheless, Melanie's Law, that went into effect October 2005,  provides that first offenders will lose their license for 180 days if they refuse the test. Second offenders lose it for three years. Third offenders for five years. Fourth offender lose it for life even if they are not ultimately convicted of drunk driving! It is my opinion that all first offenders who believe their blood alcohol level is low should now take the test. Individuals with prior convictions are, however, faced with a dilemma. Taking the test could help the prosecution put them in jail for years. As the number of prior convictions rise, and the number of years of imprisonment faced rises as well, the decision becomes more acute. There is no easy answer that will be right for all people in all  circumstances.

.Additionally, individuals who are stopped should politely refuse to submit to the field coordination (sobriety) tests offered by the officer. At that point in the stop the officer has, probably already decided to arrest you but is simply looking for additional evidence to use against you at Court.