Of course, most officers (even the instructors who teach the FST's to other officers) don't administer them properly, and don't really bother to score them at all, but instead insist that the tests are merely for the officer's benefit in forming an opinion as to whether the driver was under the influence.  In fact the tests are to be scored according to a standardized procedure and the driver either passes or fails the test based on the number of "clues" observed by the officer.  The officer is also supposed to write down the scoring, indicating each clue, right as the test is being performed... but they don't do that either.

The Standardized Tests 

The three standardized tests are the Horizontal Gaze Nystagmus (HGN) and the Walk & Turn.

The HGN test is sometimes called the "follow the finger test" because that's pretty much what the officer has you do as he slowly passes his finger or a pen or some other object back and forth about 12-15 inches in front of your eyes.  Many people think they do well on this without knowing what is being tested.  The officer is looking for involuntary jerking of the eye, something you never even notice as your eye begins to twitch.  Based on where and how much the eye twitches, the officers are supposedly able to determine with about a 70% accuracy rate whether your blood alcohol level is above or below .10.  Fortunately Tennessee courts have ruled that this evidence is inadmissible unless the prosecution brings in an expert witness to testify as to what the results actually mean.  Since the prosecution almost never does this, the results of the HGN test don't matter much in Tennessee.

The other two tests supposedly involve both testing your ability to follow directions and also to perform the tests.  The names of the Walk & Turn test and the One-Leg Stand test are both rather descriptive of what the officers requires.  The Walk & Turn test involves walking nine steps heel-to-toe (with the heel of the front foot touching the heel to the back foot each time) in a straight line without raising the arms for balance and turning in a sort of pivot-step on reaching the ninth step and then walking back, all the time counting each step out loud.  The One-Leg Stand involves standing on one leg, with your hands to your side and not raising them for balance, with the foot in the air raised about 6-12 inches off the ground right in front of the foot you are standing on, and slowly counting "One-Thousand, Two-Thousand, Three-Thousand" and so on to thirty.  Starting too soon, losing your balance, starting over or failing to understand or follow the directions all result in points added to your score even when it is scored properly.

A great many sober people can never pass the tests.  Women wearing high heels, anyone with balance problems, leg or back injuries, more than 100 pounds overweight or more than 60 years old are not even supposed to take the tests because the results are not valid.

"Reliability" of the FST's 

But there is also research indicating that the "reliability" of the FST's, even when properly administered is much lower than the police want us to believe.  The police claim that when all three of the FST's are used, the controlled tests show they are accurate 81% of the time.  This is bullshit.  Let's look at the actually study leading to the finding of this high accuracy rate.

In a controlled setting, inside, in a well lighted room, with healthy and fit "drivers" performing the tests, with no wind blowing, no one exhausted after a long drive, and no fear or anxiety such as drivers feel when pulled over at midnight, officers who had just been instructed on how to administer and score the tests were given several other officers to perform the tests on.  While one group of officers was administering the tests, another group of officers were posing as "drivers" who had just been pulled over and they were taking the tests.

Each of the officers posing as drivers and being tested had been given either no alcohol to drink or a controlled dose of alcohol which according to the officer's body weight was to be enough to bring the officer's blood alcohol level to either .05 (half way to being under the influence), .10 (under the influence) or .15 ( which most charts will tell you is the point at which there is obvious impairment, with speech being slurred and clear balance problems).  The officers being tested were equally divided into the four groups, meaning there were the same number of officers at each level.

For the sake of illustration let's say there were 25 who had nothing to drink, 25 at .05, 25 at .10, and 25 at .15.

Now all of those who had nothing to drink should have been "gimmes", anyone should have been able to get them right, since they would have had no odor of alcohol.  All of those at the .15 level also should have been gimmes because of the obvious level of impairment.  Of the remaining 50, let's say you decided whether you thought the person was impaired, with a blood alcohol level of .10 or above simply by the toss of a coin -- you would get 25 right and 25 wrong.  This would give you a total of 75 right, meaning you were right 75% of the time.... and the FST's, in the best of settings are only supposedly right 81% of the time.... a whopping 6% better than nothing.

Non-Standardized FST's 

There are also a number of other commonly used non-standardized FST's, including the following: Finger-to-Nose; Coin Pick-Up; Recite A-B-C's (generally the request is that you recite them backwards, or from one point in the alphabet to another backward); Counting (generally counting backwards, from perhaps 87 to 41); Finger Count (touching the tips of the fingers to the tip of the thumb, and usually doubling on the little finger and the index finger); Palm Pat; Tracing Mazes; Romberg Body Sway; Letter Cancellation (reading a passage and counting the number of times a particular letter appears in the passage); Math Skills (adding & subtracting).

There's a great Steve Martin movie from a few years back in which Martin's character is pulled over for DUI and the officer has him do a list of progressively more difficult FST's, each of which the driver does with ease, until the officer finally has him juggle flaming knives and read a German newspaper.  While I have never heard of an officer getting that bizarre, the bottom line is that they want you to fail the tests... and they are the only ones scoring the tests... and they will sometimes keep giving tests until they feel you have failed one.  This is why I tell people not to take the Field Sobriety Tests.  If the officer is wanting to arrest you, he's going to do so regardless how you do on the FST's, and once charged the officer will use the FST results to say you were under the influence.  By refusing to take the FST's you don't give the officer the opportunity to offer your performance as evidence you were drunk.

There are a number of other things that can indicate that a person is not impaired, including all of the following: Not Weaving, Lights Turned On, Driving At Proper Speed, Stopping At Light, Proper Turning, Responding Promptly to Lights/Siren, Pulling Over Appropriately, Understanding Officer's Directions, Ability To Respond Intelligently, Ability to Follow Directions, Not Fumbling for Wallet, Ability to Open Door, Not Leaning On Car Door, Not Stumbling While Walking, Polite, Cooperative, Respectful, Understanding Miranda warning (right to remain silent), Knowing and Voluntary and Intelligent Waiver of the Miranda Warning, Remembering Phone Numbers, Good Clean Signature, this list could be endless.  Police officers and prosecutors often like to ignore these indications a driver is not impaired, but they are real indications nonetheless.

Bottom line -- don't do the Field Sobriety Tests, not any of them... but do remain polite and courteous in your refusal.

Field sobriety tests

Police administer a one-leg-stand test after a crash.

One of the most controversial aspects of a DUI stop by a police officer involve the Field Sobriety Tests (FSTs). FSTs are heavily subjective to the opinion of the arresting officer. Many sober people are unable to perform the tests properly with a false positive rate of 23% and some are even arrested for failing the tests.[12][13][14] The walk-and-turn test is only 68% accurate, and the one-leg stand test is only 65% accurate in healthy individuals, when determining if a person is under the influence. People with medical conditions, injuries, 65 years or older, and 50 pounds or greater overweight cannot be accurately judged by these tests. The officer will administer one or more field sobriety tests (FSTs). FSTs are "divided attention tests" that theoretically test the suspect's ability to perform the type of mental and physical multitasking that is required to operate an automobile. However, these tests can be problematic for people with nonobvious disabilities affecting proprioception, such as Ehlers-Danlos syndrome. The most commonly administered FSTs include:

* horizontal gaze nystagmus test, which involves following an object with the eyes (such as a pen) to determine characteristic eye movement reaction.[15]

* walk-and-turn (heel-to-toe in a straight line). (This test is designed to measure a persons ability to follow directions and remember a series of steps while dividing attention between physical and mental tasks.[16])

* one-leg-stand.

* modified-position-of-attention (feet together, head back, eyes closed for thirty seconds; also known as the Romberg test).

* finger-to-nose (tip head back, eyes closed, touch the tip of nose with tip of index finger).

* recite all or part of the alphabet (a common myth is that the alphabet must be recited backwards, however, this is never done during an FST, as many sober people are unable to do this.).

* touch each finger of hand to thumb counting with each touch (1, 2, 3, 4, 4, 3, 2, 1).

* count backwards from a number such as 30 or 100.

* breathe into a "portable or preliminary breath tester" or PBT.

Although most law enforcement agencies continue to use a variety of these FSTs, increasingly a 3-test battery of standardized field sobriety tests (SFSTs) is being adopted. These tests are recommended by the National Highway Traffic Safety Administration (NHTSA) after studies indicated other FSTs were relatively unreliable. The NHTSA-approved battery of tests consists of the horizontal gaze nystagmus test, the walk-and-turn test, and the one-leg-stand. In some states, such as Ohio, only the standardized tests will be admitted into evidence, provided they were administered and objectively scored "in substantial compliance" with NHTSA standards (ORC 4511.19(D)(4)(b)).[17]

FSTs are more effective at determining the level of impairment than they are at estimating the driver's blood alcohol concentration (BAC). However, studies question whether the tests increase the officer's ability to judge either. In 1991, Dr. Spurgeon Cole of Clemson University conducted a study on the accuracy of FSTs. His staff videotaped individuals performing six common field sobriety tests, then showed the tapes to 14 police officers and asked them to decide whether the suspects had "had too much to drink and drive". The blood-alcohol concentration of each of the 21 DUI subjects was .00, unknown to the officers. The result: the officers gave their opinion that 46% of these innocent people were too drunk to be able to drive. This study showed the possible inaccuracy of FSTs.[18]

An increasingly used field sobriety test involves having the suspect breathe into a small, handheld breath testing device. Called variously a PAS ("preliminary alcohol screening") or PBT ("preliminary breath test"), the units are small, inexpensive versions of their larger, more sophisticated instruments at the police stations, the EBTs ("evidentiary breath test"). Whereas the EBTs usually employ infrared spectroscopy, the PAS units use a relatively simple electrochemical (fuel cell) technology. Their purpose, along with other FSTs, is to assist the officer in determining probable cause for arrest. Although because of their relative inaccuracy they were never intended to be used in court for proving actual blood-alcohol concentration, some courts have begun to admit them as evidence of BAC. [edit] Probable cause to arrest Main article: Probable cause

If the officer has sufficient probable cause that the suspect has been driving under the influence of alcohol, they will make the arrest, handcuff the suspect and transport them to the police station. En route, the officer may advise them of their Miranda rights and their legal implied consent obligation to submit to an evidentiary chemical test of blood, breath or possibly urine.

Laws relating to what exactly constitutes probable cause vary from state to state. In California it is a refutable presumption that a person with a BAC of .08 or higher is driving under the influence. However, section 23610(a)(2) of the California Vehicle Code states that driving with a BAC between .05 and .08 "shall not give rise to any presumption that the person was or was not under the influence of an alcoholic beverage."[19] [edit] Chemical test

At the police station, the arrestee will be offered a chemical test of breath, blood or, much less frequently, urine. Breath test results are usually available immediately; urine and blood samples are sent to a lab for later analysis to determine the BAC or possible presence of drugs.

If the arrestee refuses to submit to chemical testing, they will usually be booked for driving under the influence; there will be no evidence for filing the second charge of driving with .08% blood alcohol content. In some cases the arrestee may be charged with DUI even after passing a breathalyzer test if he or she refuses also to take subsequent urine or blood tests. However, the refusal will carry increased penalties on the driving under the influence charge (typically a longer license suspension and/or an increased jail sentence), and the act of refusing may be admissible in court as evidence of "consciousness of guilt". In some states, refusal to submit to a chemical test can result in an automatic suspension of driving privileges, regardless of whether the suspect is convicted of DUI.[20] In an increasing number of jurisdictions, if the suspect refuses to take a chemical test the police in some states may restrain the individual and forcefully withdraw blood.[21] This is particularly common in situations involving an accident with injury or death. In some jurisdictions this may require obtaining a warrant from a judge. Some commentators, such as Brown University's Jacob Appel, have criticized the role of medical personnel in this process. According to Appel, "If physicians acquiesce today in the removal of a resistant patient's blood, soon they may be called upon to pump the contents of an unwilling patient's stomach or even to perform involuntary surgery to retrieve an evidential bullet."[22]

While chemical tests are used to determine the driver's BAC, they do not determine the driver's level of impairment. However, state laws usually provide for a rebuttable legal presumption of intoxication at blood alcohol levels of .08 or higher (see blood alcohol test assumptions).

Breath and urine tests can only estimate the BAC at the time the test is taken, which can be different than when the vehicle was actually operated.[23] [edit] Booking and charging

If it is determined after arrest that the person's blood alcohol concentration is not at or above the legal limit of .08, they will probably be released without any charges. One may, however, still be charged with driving under the influence of alcohol on the basis of driving symptoms, observed impairment, admissions and/or performance on the field sobriety tests. And if there is suspicion of drug usage, a blood or urine test is likely, or at least the testimony of a specially-trained officer called a Drug Recognition Expert (DRE). Assuming sufficient evidence of impaired driving from drugs, the arrested may face charges of driving under the influence of drugs or the combined influence of alcohol and drugs.

Most of the time, the driver will either be kept in a holding cell (sometimes referred to as the "drunk tank") until they are deemed sober enough to be released on bail or on his "own recognizance" ("O.R."). A date to appear in court for an arraignment will be given to them. If they cannot make bail or is not granted O.R., they will be kept in jail to wait for the arraignment on remand.