Uses

• Blood alcohol content is usually used in two main arenas: criminal law and medicine. In criminal law, BAC is used to determine whether participants were legally intoxicated at the time of the act. In medicine, blood alcohol content is used to diagnose alcohol poisoning cases and make medical decisions for treatment.
  
  

Levels

• Blood alcohol content is measured in percentages. Percentages start at .01 and range to .40 or greater. Depending on the individual's tolerance, most people will exhibit some amount of intoxication at .03 percent. Risk of death and unconsciousness occurs once blood alcohol content has reached .35 percent. First time users can become unconscious with as little as .15 percent.
  
  

Parts

• An easy way to view blood alcohol content is in parts. For example, a blood alcohol content of .10 is equivalent to one part alcohol for every 1000 parts of blood.
  
  

Testing Methods

• Blood alcohol content is most commonly tested through respiration with a device called a breathalyzer. Other ways to test for blood alcohol content include examination of the saliva, urine or blood.
  
  

Legal

• The most common legal issue involving blood alcohol content is driving while intoxicated. Blood alcohol content limits vary by country. Currently in the United States, to drive a car you must have a blood alcohol content below .08 percent. Anything higher than this is illegal and can result in criminal consequences.