Medical Conditions That Mimic DUI Signs Can Lead to Criminal Charges

It's after midnight on a Saturday, and a police officer sees a car weaving slightly. After the officer pulls the vehicle over, the driver struggles to maintain his balance during a roadside field sobriety test. The driver also appears confused and has slurred speech. The officer, believing the driver has used drugs or alcohol, places him under arrest for driving under the influence (DUI).

What if the driver isn't drunk or high but is experiencing symptoms of a health condition? Some medical conditions, like diabetes and multiple sclerosis, can mimic the effects of intoxication, potentially leading to a wrongful arrest for DUI (also often called "DWI" or "Driving While Intoxicated"). These conditions can affect a person's motor skills, coordination, or cognitive abilities, causing behaviors that law enforcement officers can confuse with impairment from alcohol or drugs. Misunderstanding health conditions can lead to improper DUI arrests and, in some circumstances, wrongful convictions.

Medical Conditions That Can Mimic DUI Symptoms

The human body's reaction to certain health conditions can resemble the body's response to alcohol or drug consumption. Below are common medical conditions that could look like drug or alcohol impairment. If you think you have any of these conditions, see a medical professional for a proper diagnosis. If you believe you're having a medical emergency, get immediate medical attention.

Strokes and Seizures

Stroke and transient ischemic attacks (also called "TIAs" or "mini strokes") are serious health conditions that police officers can misidentify as drug or alcohol impairment. The acronym FAST is a good way to remember stroke symptoms (TIA symptoms generally are similar to strokes):

• F: face drooping on one side.
• A: arm weakness on one side.
• S: speech difficulty or slurred speech.
• T: time—stroke is an emergency that needs immediate attention.

Other stroke symptoms might include:

• weakness or numbness in one arm or leg, or on one side of the face
• confusion, difficulty understanding another person's statements or questions, or trouble speaking
• sudden severe headaches
• vision problems in one or both eyes, and
• dizziness, difficulty walking, coordination problems, or lack of balance.

A stroke or TIA requires immediate medical attention—if you believe you are experiencing one, ask for immediate medical attention. If you think you have had a TIA, see a medical professional. According to the Mayo Clinic, one in three people who've had a TIA will have a stroke, often within hours or days of the TIA.

In most cases, police officers will eventually recognize that a person isn't intoxicated but is having a stroke—but a delay in recognizing a stroke can be deadly or can cause permanent disabilities. TIAs might not have lasting consequences and can last for only a few minutes to several hours. Because TIAs tend to be shorter than strokes, it's more likely that the police won't recognize the symptoms and will charge a driver with a DUI.

Seizures can result from many different disorders and conditions. In many instances, a seizure will be easy to distinguish from alcohol or drug impairment. However, some types of seizures can have symptoms similar to impairment, especially during the period of recovery after a seizure. These seizure symptoms can include confusion, dizziness, trouble speaking, memory issues, disorientation, memory problems, blurred vision, and unsteady movement.

Multiple Sclerosis and Parkinson's

Multiple sclerosis (MS) and Parkinson's disease are chronic conditions with symptoms that can arise at unpredictable times. MS can cause weakness, loss of balance, dizziness, vision problems, spasms, tremors, memory issues, and speech difficulties. The symptoms of MS depend on the person and the type of MS.

Parkinson's disease is a disorder of the nervous system with symptoms that gradually appear and that might not be noticeable at first. As with MS, Parkinson's symptoms can be different from person to person. Typical symptoms include tremors, slower movements, rigid muscles, balance problems, and speech issues (including slurred speech).

Diabetes

Diabetic emergencies can be easily misidentified as drug or alcohol impairment in DUI cases. Hypoglycemia (low blood sugar) can cause the following DUI-like symptoms:

• sweating
• shakiness
• confusion
• drowsiness
• dizziness
• blurred vision
• difficulty speaking, and
• loss of consciousness.

Hyperglycemia (high blood pressure) can cause the following symptoms:

• frequent urination
• blurred vision
• weakness
• nausea and vomiting, and
• a fruity smelling breath (that can be confused with the odor of alcohol).

An officer who is untrained in detecting signs of diabetes emergencies might believe a driver is impaired. A delay in getting proper treatment can lead to coma, permanent brain damage, or death.

Head Injuries

Head injuries can arise from a direct blow to the head or sudden jerking motion (such as whiplash from a car accident). These injuries can cause bruising to the brain and damage to brain tissue and blood vessels in the brain. Head injury symptoms, even mild head injuries, can mimic symptoms of alcohol and drug impairment, including:

• confusion
• balance problems
• difficulty walking
• nausea and vomiting
• dizziness
• memory and concentration issues
• blurred vision, and
• slurred speech.

A police officer could confuse the symptoms of a head injury, including concussions, with intoxication.

Thyroid Issues

Hyperthyroidism (when the thyroid gland produces too much thyroid hormone) can produce symptoms similar to typical signs of impairment, such as sweating, hand tremors, anxiety, nervousness, and irritability.

Arrhythmias and Heart Attacks

Some symptoms of irregular heartbeats (arrhythmias) and heart attacks are also common symptoms of drug and alcohol impairment. Cardiac arrhythmia symptoms include dizziness, fainting, and lightheadedness.

Heart attack symptoms can vary depending on the person and the severity of the heart attack. Symptoms might include lightheadedness, dizziness, and nausea.

Psychological Conditions

Numerous psychological conditions can create physical symptoms and behavior changes. For instance, panic attacks can cause trembling, sweating, nausea, and numbness in the fingers and toes.

According to the Cleveland Clinic, psychosis, a collection of symptoms caused by different mental health conditions, occurs when a person experiences a disconnection from reality. Psychosis symptoms can be caused by drug use, but they also can look like drug use symptoms when a person hasn't used drugs.

Inner Ear Issues

The inner ear is important for hearing, but it's also the center of the body's vestibular system, which regulates balance. Inner ear disorders and infections can cause balance problems, vertigo (a spinning sensation), and dizziness.

Sleep Deprivation

Severe sleep deprivation can cause reduced logical reasoning, slower reaction times, microsleeps (a short, unplanned period of sleep), mood changes, and trouble paying attention. Microsleeps can cause accidents (which can be mistakenly attributed to impairment), and the reduction in logical reasoning can cause issues with performing simple tasks.

Even if you're sober, you shouldn't drive when sleep-deprived. If you're in an accident because of sleep deprivation, you could face charges like reckless driving and vehicular homicide, depending on your state's laws. A car accident caused by drowsy driving can also lead to civil liability for damages caused by the accident.

Medication Interactions

Whether you take prescription or over-the-counter medications, you should make sure that they are safe to use before driving. Medication interactions can create sedation, confusion, and coordination problems. Unlike other medical conditions, using legal drugs can result in a DUI conviction. If the drug's warning label says it causes drowsiness or that you should avoid operating a vehicle, you could be charged and convicted of a DUI if the drug impairs you to an extent that violates your state's DUI law.

Why Medical Conditions Are Often Mistaken for DUI

With so many different types of medical conditions that can mimic being under the influence, it's easy to see why they can be confused with impairment. Several factors can contribute to the misidentification of medical conditions as DUI cases.

Officer Training Limitations

Many law enforcement officers receive excellent and extensive training on DUI investigations. At the same time, most police officers aren't trained medical professionals who can easily recognize the various health conditions that can look like alcohol or drug impairment. The field sobriety tests that officers administer during a DUI stop can help detect intoxication, but they might not account for medical conditions that can cause a driver to perform poorly on field sobriety tests. (Read more about field sobriety tests below.)

Unpredictability of Some Medical Conditions

Sometimes, drivers might not know they are suffering from a medical condition. They might have had a condition for a while without being diagnosed, might have symptoms from a recent concussion they're unaware of, or could be experiencing a sudden condition like a stroke. A driver who's aware of a medical condition can let the officer know about it, and the officer can take steps to avoid misidentifying the medical condition as intoxication (such as skipping certain field sobriety tests or getting a blood test instead of a breath test). If a driver is unaware of a health issue, then the investigating officer could easily assume every observed symptom is a result of drug or alcohol impairment.

Confirmation Bias

Officers who suspect DUI might unconsciously look for evidence to confirm their initial suspicion. For instance, if almost every person an officer pulls over for erratic driving ends up with a BAC above .08%, then the officer might automatically assume a driver who's driving erratically is intoxicated. The officer might unintentionally overlook signs that could suggest a health condition as the cause of the driver's behavior because they've already made up their mind, even if unconsciously, that the driver is drunk. Instead, the officer might see every misstep, trembling hand, or slurred word as confirming the suspicion that the driver is drunk. Looking for clues to confirm a suspicion while ignoring evidence that contradicts that assumption is a normal human tendency called "confirmation bias."

Employment Pressure

Many police departments and prosecutors consider DUI enforcement a high priority. Some jurisdictions might have additional public pressure to get drunk drivers off the road. One way for a police department to appease the public is to show high numbers of DUI arrests and convictions. These pressures can trickle down to police officers and can cause less careful officers to make an arrest without noticing alternative reasons for the driver's behavior.

Field Sobriety Tests vs. Medical Reality

Field sobriety tests (FSTs) are common investigative tools used by police officers during DUI stops. There are two types of FSTs: standardized FSTs and non-standardized FSTs. In the 1970s, the National Highway Traffic Safety Administration (NHTSA) conducted studies to develop FSTs to detect alcohol impairment. The studies resulted in three standardized FSTs: the horizontal gaze nystagmus (HGN) test, the walk and turn test, and the one-leg stand test.

The Three Standardized Tests

During the (HGN) test, an officer looks at the driver's eyes while moving a stimulus—often a pen—in the driver's field of vision. The officer looks at the driver's eyes for signs of nystagmus (involuntary jerking movements).

The walk-and-turn test requires an individual to walk nine heel-to-toe steps in a straight line, turn around, and walk back nine heel-to-toe steps while maintaining balance and following specific instructions.

The one-leg stand test asks the person to stand on one foot, with the other foot raised 6 inches, for 30 seconds while counting aloud and keeping both legs straight and both arms by the side of the body.

These three tests are fairly accurate on their own, but their results are even more accurate when all three tests are conducted together. According to a guide from the American Prosecutors Research Institute's National Traffic Law Center (NTLC), studies showed that all three tests used together accurately determined a person's BAC was .10% or higher 83% to 93% of the time. A 1983 NHTSA study showed that, when conducted individually, the tests weren't as accurate, with HGN only 77% accurate, one-leg stand 65% accurate, and walk and turn 68% accurate. Later studies cited by the NTLC show that HGN accurately determined a BAC of .10% or above 96% of the time when using HGN alone.

Non-Standardized Tests

There are a lot of non-standardized FSTs that officers might use during a DUI stop. A few of these tests are:

• reciting the alphabet (sometimes starting in the middle of the alphabet with a letter chosen by the officer)
• counting backwards, and
• counting while tapping the thumb to each finger on the same hand.

These tests haven't been accepted as accurate by NHTSA. Because they don't have the same level of reliability, some judges might prohibit officers from testifying about these tests in court.

Medical Reality Check

Even though the standardized FSTs have some level of proven reliability, many medical conditions can affect their results. Nystagmus can be caused by several health conditions, including inner ear disorders, strokes, brain tumors, certain medications, brain injuries, and MS.

People with leg injuries, neurological conditions, or other medical conditions that cause balance disorders can struggle with the walk and turn and one-leg stand tests, whether or not they are under the influence of drugs.

Properly trained officers will ask if a person has any medical conditions that will prevent successful completion of the FSTs. But the human body is complex, and there could be situations where a person doesn't know they have a health condition or emergency, such as a stroke or concussion.

Legal Defenses and Strategies When Medical Conditions Are Involved

Using a medical condition to challenge a DUI charge is complicated and likely will require medical records and a medical expert. When raising medical conditions as a defense to a DUI, there are two main approaches to get the case dismissed:

• challenge the probable cause for the arrest, and
• challenge the prosecution's evidence of impairment.

When health conditions are mistaken for DUI, several legal defense strategies might be available, depending on the jurisdiction and the specific circumstances of the case. Most strategies to defeat probable cause at a motion to suppress hearing can also be used to challenge evidence of impairment at a DUI trial.

Challenging the Legality of an Arrest

To arrest a driver for a DUI, a police officer must have probable cause that the driver is under the influence of drugs or alcohol. Probable cause isn't as high a standard as "beyond a reasonable doubt," which is the standard required to convict someone of a DUI. Because probable cause is a lower standard, it's easier for the prosecution to establish probable cause—and that the arrest was legal—than it is to prove that a driver is guilty of DUI.

However, if the officer based the decision to arrest solely on behavior caused by a diagnosed medical condition (especially if the officer knew about or should have recognized the medical condition), then it might be possible to challenge probable cause by filing a motion to suppress. If the motion is successful, the court will throw out evidence acquired after the arrest, such as a breath or blood test or post-arrest statements. If the prosecution can't use that post-arrest evidence, it might need to dismiss its case.

Challenging Evidence of Impairment

There are two main types of DUI: an impairment DUI and a "per se" DUI.

A per se DUI allows a court to find drivers guilty if they have a blood alcohol content (BAC) above a certain level (.08% in all states but Utah, where it's .05%) or have specific drugs in their blood. If you took a blood or breath test after your DUI arrest that shows a drug or alcohol level above the limit, then the prosecution doesn't need to show that the drugs or alcohol actually impaired you to convict you.

Unlike a per se DUI, an impairment DUI requires the prosecution to present evidence that drugs or alcohol affected the driver's ability to operate a vehicle. If you have a diagnosed medical condition that makes you appear drunk or high, then you might be able to convince a judge or jury that you weren't impaired and that you should be found not guilty.

Challenging FSTs and the Officer's Observations

FSTs usually are important evidence for the prosecutor to establish probable cause for an arrest. But judges often will allow the prosecutor to use FSTs, especially standardized FSTs, as evidence of the driver's guilt at trial, too. The prosecutor also can use the officer's general observations about the driver's appearance, driving behavior, and speech to establish probable cause and guilt.

When attacking FSTs in general, defense attorneys often attack the officer's training and understanding of FSTs. An attorney also might argue that the FSTs were conducted in poor conditions (such as cold or hot weather, poor lighting, heavy traffic nearby, and uneven surfaces for the walk and turn and one-leg stand).

When a driver has a medical condition, the attorney likely will argue that FSTs are unreliable when administered to someone with that condition. An attorney might question the officer about medical conditions' effects on FSTs. An attorney can also use a medical condition to explain away poor driving behavior, slurred speech, and other observations of the driver's appearance, behavior, and balance.

Presenting Evidence of a Medical Condition

In a criminal case, a defendant has no duty to present evidence of innocence—that includes a defendant's right to not take the witness stand and testify. A judge or jury can't assume that the defendant's silence or decision not to present evidence is proof of the defendant's guilt. However, in the vast majority of cases, the defense will need to give some evidence to rebut the prosecutor's evidence. And the defendant might need to testify to put forward the strongest defense. The decision to present evidence or testify can be difficult, and the wrong decision can have serious consequences. A defense attorney with a strong knowledge of DUI trials is practically a necessity when going to trial on a DUI case.

When using a medical condition to explain away a DUI charge, the driver generally will need to show that the FST results and the officer's observations were caused by a legitimate health condition rather than drug or alcohol impairment. Medical records, expert testimony, and witness statements about the driver's condition are typical ways to establish a medical condition. The defendant also can decide to testify about a health issue, but that testimony will only be stronger if supported by medical records and expert testimony.

Expert Medical Testimony

Medical experts can provide crucial testimony to explain how the defendant's specific condition can mimic intoxication symptoms. For instance, a neurologist might tell the jury about stroke symptoms and how they might be confused with intoxication. Doctors who have treated the driver can give the jury their diagnosis. Medical experts can also review medical records and the police report to form a medical opinion about the driver's behavior on the night of the arrest.

Medical Records

Comprehensive medical records can be essential evidence when a health issue is a defense to a DUI charge. Emergency room records, whether immediately after the arrest or days later, showing a medical condition that could've affected the driver on the day of the arrest can be powerful evidence of innocence. Long-term medical records that show the driver has a condition can also explain why the driver was experiencing symptoms when arrested.

Other Witness Statements

Family members, friends, and coworkers can tell the judge or jury that they've seen the driver's symptoms before and that they're not unusual. Friends who were with the driver on the night of the arrest can also explain that they never saw the driver use alcohol or drugs—or that the driver never uses alcohol or drugs if that's the case.

The Driver's Testimony

Drivers who choose to testify can explain what they were experiencing during the DUI stop and arrest. If they have a history of symptoms, they can tell the jury and judge about those symptoms. If the symptoms were the result of a new or sudden issue, like a stroke, their testimony can help strengthen a medical expert's opinion. But remember that testifying can be a huge risk with little reward, so discuss the decision with your attorney if you're charged with a DUI.

What to Do If You're Arrested Due to a Medical Condition

Being arrested for DUI when you're experiencing a medical emergency can be terrifying and disorienting. But don't let your fear of being arrested prevent you from asking for help. Many police officers don't have the training to recognize every possible medical emergency, so don't assume the officer knows that you're in distress. Be specific about your symptoms and any conditions you know you have.

Even if you're not experiencing an emergency, you must clearly tell the arresting officer about any medical conditions you have that could affect your performance on FSTs and overall appearance and demeanor. When speaking with the police, be respectful and avoid arguing and shouting.

Contact a DUI attorney as soon as possible. An attorney can help you gather evidence, like medical records, and can help get a medical expert to review those records.

Finally, if your medical issue wasn't an emergency and didn't require hospitalization or treatment when you were arrested, you should still consider following up with your primary physician or another medical professional.

Getting Help From a DUI Attorney

If your medical condition led to a DUI arrest, you should hire a qualified DUI attorney. The consequences of a conviction are too serious—and a medical defense is too complex—to try to handle your case on your own.