This description of the One Leg Stand test posted by California DUI Lawyer.

In the "DWI Detection and Standardized Field Sobriety Testing" student manual it emphasizes one final and major point. The validation of these tests applies only when the tests are administered in the prescribed, standardized manner; and only when the standardized clues are used to assess the suspect's performance; and only when the standardized criteria are employed to interpret that performance. It is reiterated that "If any one of the Standardized Field Sobriety test elements is changed, the validity is compromised. 

In the "DWI Detection and Standardized Field Sobriety Testing" student manual it emphasizes one final and major point. The validation of these tests applies only when the tests are administered in the prescribed, standardized manner; and only when the standardized clues are used to assess the suspect's performance; and only when the standardized criteria are employed to interpret that performance. It is reiterated that "If any one of the Standardized Field Sobriety test elements is changed, the validity is compromised.