What is the test for driving under the influence of alcohol?

contacted appellant and two other men in a closed park after midnight. (People v. Keshmiri, supra, G054606, at p. 2.) Noticing signs the men had been drinking, the officer advised them not to drive, and they assured him they would not do so. (Id. at pp. 2-3.) But as soon as the officer was out of sight, they got into their cars and began driving away. (Id. at p. 3.) When the officer circled back to the area, he stopped their vehicles and found appellant behind the wheel of one of them. "Smelling of alcohol and unable to pass a field sobriety test, appellant was arrested at the scene. A subsequent blood test revealed his blood alcohol level was twice the legal limit." (Ibid.)