This description of the Walk and Turn test posted by San Francisco DUI Lawyer.

The officer must observe the suspect from three or four feet away and remain motionless while the suspect performs the test. Being too close or excessive motion may affect the reliability of this test. The officer must give good verbal instructions and accompany the test with a complete demonstration. The suspect must understand the instructions and acknowledge understanding prior to the test beginning. The officer should document that affirmative response. This test is scored in relation to eight scoring factors that can be seen in two separate stages. The first stage of this test is called the Instruction Stage. 

This will set the stage for the entire test. If the officer does not follow training and procedure during this stage, it may affect the validity of the entire test. The officer must verbally tell the suspect to place their left foot on the line and to place their own left foot on the line during demonstration. The person is then told to place their right foot on the line, ahead of their left foot, with the heel of the right foot against the toe of the left foot. This is also demonstrated. The person is then told to place their arms down at their side. They are instructed to maintain this position until told to begin and not to start until told to do so. They must then indicate an understanding of the test after being asked if they understand.