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Texas SFST Program

The Texas Standardized Field Sobriety Testing Program• Grant-funded through the National Highway Traffic

Safety Administration and the Texas Department of Transportation.

• Provide free training to Texas Peace Officers in DWI Enforcement and the Standardized Field Sobriety Tests (SFST).

• The “go-to” organization for the SFST curriculum in Texas and a resource for questions about DWI enforcement.

What do we teach?

• 24-hour SFST Practitioner course

• 50-hour SFST Train-the-Trainer Instructor course

• 8-hour SFST Refresher course

• 8-hour Fundamentals of DWI Investigation and Enforcement

• Full-time staff of 5 as well as 52 adjunct instructors from around the state.

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When do you know someone is drunk?

What does the law say?

• Penal Code 49.04 Driving While Intoxicated

(a) A person commits an offense if the person is intoxicated while operating a motor vehicle in a public place.

• Definition of "Intoxicated" means:

• (A) not having the normal use of mental or physical faculties by reason of the introduction of alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body; or

• (B) having an alcohol concentration of 0.08 or more

Three Phases of DWI Detection

• Vehicle in Motion

• Personal Contact

• Pre-Arrest Screening

Officers make a decision based on the “totality of the circumstances”.

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Vehicle in Motion

Starts with the initial observation of the vehicle in

operation

The decision as to whether to stop the vehicle

The observation of the stop

Stops need only be based on reasonable suspicion.

Effects of Impairment on Drivers

• Slowed reactions

• Impaired judgment –

willingness to take risks

• Impaired vision

• Poor Coordination

Blood Alcohol Concentration

0.08

ImpairedVision

0.05

ImpairedJudgment

0.03

SlowedReactions

0.10

PoorCoordination

Recognition of the Initial Cues

What does the officer see:

• Moving violation?

• Equipment violation?

• Other violation?

• Unusual operation?

• Anything else?

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Personal Contact

The interview and observation of the driver

The decision whether to have the driver exit the vehicle

The observation of the exit

What is the officer looking for?

• What do they see?

• What do they hear?

• What do they smell?

Some of the things officers observe

• Bloodshot eyes• Soiled clothing• Fumbling Fingers• Alcohol Containers• Drugs/Paraphernalia• Bruises, bumps,

scratches• Slurred speech• Admission of drinking

• Inconsistent responses• Unusual statements• Abusive language• Alcoholic beverage odor• Marihuana• Cover up odors• Unusual odors

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Interview of the suspect

• It is during the personal contact stage that the officer gathers information from the suspect

• At this time multiple signs of intoxication may occur

• Slurring, mumbled speech

• Confusion, slow response to questions and directions

• Slow or careful movements

Pre-Arrest Screening

• Standardized Field Sobriety Tests• Horizontal Gaze Nystagmus• Walk and Turn• One Leg Stand

Where did the tests come from?

• Ft. Lauderdale study 1975• After face-to-face contacts and testing of drivers, officers only

correctly identified drivers who were 0.10 to 0.20 BAC 22% of the time.

• NHTSA contacted with SCRI to develop more accurate tests

• California 1977 Lab study• California 1981 Lab and Field studies• Maryland, Washington DC, Virginia, and North Carolina 1983

–Field study

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Research results

Original Results 1981 0.10 BAC• HGN by itself – 77%

• Walk & Turn by itself– 68%

• One Leg Stand by itself – 65%

San Diego Study 1998 –0.08 BAC• HGN by itself – 88%

• Walk & Turn by itself – 79%

• One Leg Stand by itself – 83%

4 clues on HGN, 2 clues on W&T, and 2 clues on OLS

What do they learn from the tests?

• Officers are looking for clues• Horizontal Gaze Nystagmus – max of 6 clues; min 4 clues• Walk and Turn – Max of 8 clues; min of 2• One Leg Stand – Max of 4 clues; min of 2

The officer does not have to have the minimum number of clues on each test to make a determination that the person is intoxicated.

Totality of the circumstances.

So what are the clues?HGN –1st they check for Equal Pupil Size, Resting Nystagmus, & Equal Tracking to determine if the driver is a candidate.

The officer looks for three clues in each eye, in this order:

1. Lack of Smooth Pursuit

2. Distinct and Sustained Nystagmus at Maximum Deviation

3. Onset of Nystagmus Prior to 45 degrees.

The officer then checks for Vertical Gaze Nystagmus – this is not a clue, rather an observation. It may be present in those under the influence of high doses of alcohol for that individual or some other drugs.

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Horizontal Gaze Nystagmus

A clue may be present in one eye, but not in another eye.

A driver may still be over a 0.08 BAC, but have fewer than 4 clues.

There are three categories of drugs which cause HGN:

• Central Nervous System Depressants

• Dissociative Anesthetics

• Inhalants

Walk & Turn and One Leg Stand

Walk and Turn

The 8 clues are:• Can’t balance during

instructions• Starts too soon• Uses arms for balance• Misses heel to toe• Steps off line• Improper turn• Incorrect number of steps• Stops while walking

One Leg Stand

The four clues are:

• Puts foot down

• Uses arms for balance

• Sways while balancing

• Hops

*Specific Criteria is set for each clue in all three tests

What other tests do they use?

There are other valid tests that can be used, but no others that have been validated.

• Finger Count

• Finger to Nose

• Paper Trace

• Counting

• Alphabet

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When do officers use other tests?

To supplement the SFST or when the driver is not a candidate for the tests, due to an injury, disease or other physical condition.

Emerson vs. State (Texas Ct. of Crim. App 1994)

• Allows a properly trained officer to testify about the Horizontal Gaze Nystagmus test.

• Requires that the officer must follow the HGN technique as taught by NHTSA and the State of Texas.

QUESTIONS?

VALIDATION OF THE STANDARDIZED F IELD SOBRIETY TEST

BATTERY AT BACS B ELOW 0.10 PERCENT

FINAL REPORT

Submitted to:U.S. DEPARTMENT OF TRANSPORTATION

NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

Jack StusterMarcelline Burns

August 1998

ANACAPA SCIENCES, INC.P.O. Box 519

Santa Barbara, California 93102

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Technical Report Documentation Page

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1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No.

DOT HS ?

4. Title and Subtitle 5. Report Date

Validation of the Standardized Field Sobriety Test Battery at August 1998BACs Below 0.10 Percent

7. Author(s) 6. Performing Organization Code: n/aJack W. Stuster, PhD, CPE, and Marcelline Burns, PhD 8. Performing Organization Report No. n/a

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)Anacapa Sciences, Inc.P.O. Box 519 11. Contract or Grant No.Santa Barbara, CA 93102 DTNH22-95-C-05192

12. Sponsoring Agency Name and Address 13. Type of Report and Period CoveredNational Highway Traffic Safety Administration Final Report400 Seventh Street, SWWashington, D.C. 20590

15. Supplemental Notes 14. Sponsoring Agency CodeJames F. Frank, PhD was the Contracting Officer’s TechnicalRepresenative (COTR) for this project.

16. Abstract

This study evaluated the accuracy of the Standardized Field Sobriety Test (SFST) Battery to assist officers inmaking arrest decisions for DWI at blood alcohol concentrations (BACs) below 0.10 percent. NHTSA’s SFST batterywas validated at 0.10 percent BAC in 1981. The trend to reduce statutory DWI limits to 0.08 percent BAC promptedthis research project.

The research was composed of several project tasks, including planning, site-selection, training, data entry, anddata analysis, in addition to the actual conduct of a major field study. The City of San Diego, California, was selectedas the site. Seven officers of the San Diego Police Department’s alcohol enforcement unit were trained in theadministration and modified scoring of NHTSA’s SFST battery (i.e., Horizontal Gaze Nystagmus-HGN, Walk and Turn,and One Leg Stand). SFST scoring was adjusted: the observation of four HGN clues indicated a BAC ≥0.08 percent(rather than four clues indicating a BAC ≥0.10 percent), and the observation of two HGN clues indicated a BAC≥0.04 percent. During routine patrols, the participating officers followed study procedures in administering SFSTsand completing a data collection form for each test administered. The officers’ final step in each case was theadministration of an evidentiary breath alcohol test.

Data analysis found the SFSTs to be extremely accurate in discriminating between BACs above and below 0.08percent. The mean estimated and measured BACs of the 297 motorists tested were 0.117 and 0.122, respectively;the difference between the means (0.005 percent BAC) is very small and operationally irrelevant. Further, analysesfound the HGN test to be the most predictive of the three components of the SFST battery (r=0.65), however ahigher correlation was obtained when the results of all three tests were combined (r=0.69).

Decision analyses found that officers’ estimates of whether a motorist’s BAC was above or below 0.08 or 0.04percent were extremely accurate. Estimates at the 0.08 level were accurate in 91 percent of the cases, or as high as94 percent if explanations for some of the false positives are accepted. Officers’ estimates of whether a motorist’sBAC was above 0.04 percent but lower than 0.08 percent were accurate in 94 percent of the decisions to arrest andin 80 percent of cases overall. Also, the officers and prosecutors who were interviewed about the SFSTs found thetest battery to be acceptable for field use to establish probable cause for DWI arrest.

The results of this study provide clear evidence of the validity of the Standardized Field Sobriety Test Battery todiscriminate at 0.08 percent BAC, using a slightly modified scoring procedure. Further, study results stronglysuggest that the SFSTs also accurately discriminate at 0.04 percent BAC.

17. Key Words 18. Distribution StatementDWI, DUI, detection, field sobriety, performance tests,alcohol, law enforcement, highway safety

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. PriceUnclassified Unclassified

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Final ReportValidation of the SFST Battery at BACs Below 0.10 Percent

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EXECUTIVE SUMMARY

This report documents the research activities and presents the results of astudy conducted for the National Highway Traffic Safety Administration (NHTSA)to evaluate the accuracy of the Standardized Field Sobriety Test (SFST) Battery toassist officers in making arrest decisions and to discriminate blood alcoholconcentrations (BACs) below 0.10 percent. NHTSA’s SFST battery was validated at0.10 percent BAC in 1981. The trend to reduce statutory DWI limits to 0.08 percentBAC prompted this research project.

DESCRIPTION OF THE RESEARCHThe research was composed of several project tasks, including planning, site-

selection, training, data entry, and data analysis, in addition to the actual conduct ofa major field study. The City of San Diego, California, was selected as the site of thefield study. Seven officers of the San Diego Police Department’s alcohol enforcementunit were trained in the administration and modified scoring of NHTSA’s SFSTbattery (i.e., Horizontal Gaze Nystagmus, Walk and Turn, and One Leg Stand). SFSTscoring was changed slightly: the observation of four horizontal gaze nystagmus(HGN) clues indicated a BAC ≥0.08 percent (rather than four clues indicating a BAC≥0.10 percent), and the observation of two HGN clues indicated a BAC ≥0.04 percent.During routine patrols, the participating officers followed study procedures inadministering SFSTs and completing a data collection form for each testadministered during the study period. The officers’ final step in each case was theadministration of an evidentiary breath alcohol test.

RESULTSThe participating officers completed a total of 298 data collection forms; only

one case was eliminated from analysis because the motorist refused all forms ofBAC testing. Data analysis found the SFSTs to be extremely accurate indiscriminating between BACs above and below 0.08 percent. The mean estimatedand measured BACs of the 297 motorists tested were 0.117 and 0.122, respectively;the difference between the means (0.005 percent BAC) is very small andoperationally irrelevant. Further, analyses found the HGN test to be the mostpredictive of the three components of the SFST battery (r=0.65), however a highercorrelation was obtained when the results of all three tests were combined (r=0.69).

The results of decision analyses provide clear indication of SFST accuracy.Decision analyses found that officers’ estimates of whether a motorist’s BAC wasabove or below 0.08 or 0.04 percent were extremely accurate. Estimates at the 0.08level were accurate in 91 percent of the cases, or as high as 94 percent if explanationsfor some of the false positives are accepted. Officers’ estimates of whether amotorist’s BAC was above 0.04 but under 0.08 were accurate in 94 percent of thedecisions to arrest and in 80 percent of the relevant cases, overall.

Final ReportValidation of the SFST Battery at BACs Below 0.10 Percent

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Finally, the officers and prosecutors who were interviewed about the SFSTsfound the test battery to be fully acceptable for field use to establish probable causefor DWI arrest.

IMPLICATIONSThe results of this study provide clear evidence of the validity of the

Standardized Field Sobriety Test Battery to discriminate above or below 0.08 percentBAC, using a slightly modified scoring procedure. Further, study results stronglysuggest that the SFSTs also accurately discriminate above or below 0.04 percent BAC.