Suspicion of DUI (Driving Under the Influence) means that a police officer believes a driver might be impaired by alcohol or drugs. It is the initial stage of a DUI investigation, before any formal charges are laid or proven in court. In practice, an officer’s reasonable suspicion that a driver has committed a crime (such as impaired driving) is what legally justifies stopping and briefly detaining the driver. Every DUI arrest begins with suspicion – the officer observes something that suggests the driver may be intoxicated. It’s important to note that suspicion is not the same as a charge or conviction; it simply means the officer has cause to investigate further.
In Canada (including Toronto), the Criminal Code doesn’t actually use the term “DUI” – it speaks of “impaired driving” or “operating while intoxicated.” However, Canadians commonly use “DUI” in conversation to refer to the offense. So if an Ontario police officer says you were stopped on suspicion of DUI, it means suspected impaired driving. The key point is that the officer saw or sensed something that made them suspect you weren’t sober enough to drive.
Common Reasons for DUI Suspicion
Police cannot pull drivers over arbitrarily – they need a valid reason (reasonable suspicion) to initiate a traffic stop. What triggers an officer’s suspicion of DUI? There are well-recognized red flags that police look for on the road. Some common signs include:
- Erratic driving: Weaving in and out of lanes, drifting across the center line, or swerving without reason.
- Traffic violations: Speeding, running red lights or stop signs, making illegal turns, or frequent braking for no apparent reason. These driving errors can suggest impaired judgment or slowed reaction time.
- Driving too slow or stopping randomly: Impaired drivers sometimes drive significantly under the speed limit or halt in the road unexpectedly.
- Nearly hitting objects or other cars: Close calls, like almost striking a curb, another vehicle, or roadside objects, may indicate poor coordination.
- Physical indicators at a stop: Even if you were stopped for a minor infraction (like a broken taillight), an officer might develop suspicion of DUI if they notice bloodshot eyes, slurred speech, fumbling with documents, or the smell of alcohol or cannabis when talking to you. The odor of alcohol on a driver’s breath, in particular, can quickly provide reasonable suspicion of impairment.
It’s worth noting that an officer’s hunch isn’t enough – the suspicion must be based on specific, observable facts. For instance, feeling that a driver “looked drunk” is too vague, but observing them miss traffic signals and smell of alcohol would be considered specific and articulable facts justifying further investigation.
Reasonable Suspicion vs. Probable Cause
“Suspicion of DUI” is tied to the legal concept of reasonable suspicion, which is the threshold for an officer to initiate a stop and investigation. This is a lower standard than probable cause, which is required to make an arrest or lay charges. In simple terms, reasonable suspicion means the officer has some reason to believe you might be impaired (enough to investigate), whereas probable cause means they have strong evidence leading them to conclude you likely committed the offense (enough to arrest and charge you).
For example, weaving between lanes and smelling of alcohol would give an officer reasonable suspicion to stop you and check for DUI. If during the stop you fail sobriety tests or blow over the legal limit on a breath test, that provides probable cause for arrest. An officer cannot arrest you for DUI on suspicion alone without further evidence – they must reach the higher probable cause standard by observing more evidence of impairment.
What happens if an officer lacks reasonable suspicion for the stop in the first place? In that case, any evidence gathered (like breathalyzer results) may be ruled inadmissible in court for violating your rights. In other words, a DUI case can be dismissed if the initial stop was not justified. Even if you were over the limit, the charge might not stick if the officer had no valid reason to pull you over. Courts take the legality of the stop seriously – an example described by one law firm shows that if you were stopped with no traffic violation or cause, evidence of DUI obtained afterward would likely get thrown out and the DUI charge would be dismissed.
What Happens When You’re Pulled Over on Suspicion of DUI?
Once an officer has stopped you due to suspicion of DUI, they will begin a DUI investigation on the roadside. Typically, the officer will engage you in conversation, ask if you’ve been drinking, and observe your responses. They are looking for further clues of impairment (slurred speech, confusion, alcohol odor, etc.). At this stage, it’s crucial to remember you have rights (more on that below) and that anything you say can be used as evidence.
An officer conducts a field sobriety test (checking a driver’s eye movement) during a roadside DUI investigation. Field sobriety tests are used to gather evidence of impairment when someone is suspected of drunk driving.
Often, the next step is asking the driver to perform Field Sobriety Tests (FSTs). These are physical and cognitive tests designed to gauge impairment. Common FSTs include the walk-and-turn test (walking in a straight line heel-to-toe and turning), the one-leg stand test, and the horizontal gaze nystagmus test (where you follow a pen or light with your eyes). The officer looks for indicators like loss of balance, inability to follow instructions, or jerky eye movements. Poor performance on these tests can bolster the officer’s suspicion into probable cause for a DUI arrest. However, it’s worth noting that field tests are not foolproof – medical conditions, nerves, or even fatigue can affect performance. Still, officers and courts do use them as evidence of impairment.
In many cases, especially if you show some signs on the field tests, the officer will also request a breath test using a handheld roadside device (often called a breathalyzer or Approved Screening Device in Canada). This device estimates your Blood Alcohol Concentration (BAC) from your breath sample. If the reading is above the legal limit (which is 0.08% BAC in Canada and most U.S. states), that gives the officer strong grounds to arrest you for DUI and take you to the police station for further testing. Even if the roadside device shows a “warn range” (for example, 0.05 – 0.079% BAC in Ontario), police in Ontario can impose an immediate license suspension and other penalties on the spot, and they may require further tests.
⚖️ Canadian Note: Thanks to a 2018 change in Canadian law, police now have the power of Mandatory Alcohol Screening – they can demand a breath sample from any lawfully stopped driver, even without specific suspicion of alcohol in the body. This means if you’re pulled over for any reason in Toronto (say a broken tail light or at a R.I.D.E. checkpoint), the officer can require a breath test on the spot. Refusing this roadside test is an offense on its own. So, while traditionally an officer needed to smell alcohol or notice signs of impairment before testing, today every traffic stop can potentially lead to a breath test. Of course, if you haven’t been drinking, you’ll pass the test and be on your way. If you blow over the limit or refuse, you will be arrested for DUI or for refusal.
A police officer administers a roadside breathalyzer test to a driver suspected of DUI. Portable breath tests help officers determine if there is probable cause to arrest for drunk driving.
After the field sobriety and breath tests, one of three things typically happens:
- If you pass the tests (no clear signs of impairment): You might be let go with either a warning or just a ticket for the original infraction (if any). The “suspicion of DUI” ends when the officer concludes you’re likely not impaired after all.
- If you fail or show evidence of impairment: The officer will place you under arrest on suspicion of DUI. This means you’ll be handcuffed and taken to the station. At the station, a more accurate breath test on an approved instrument (or a blood test in some cases) will be done to gather official evidence of your BAC.
- If you refuse to cooperate with tests: In many jurisdictions (including Ontario), refusing a breath test or field sobriety tests is treated similarly to a DUI offense. The officer can arrest you for refusal, and you’ll face penalties as if you were convicted of impaired driving in many respects. (More on implied consent and refusals below.)
Throughout this process, it’s critical to remain polite and avoid sudden movements, as the police are assessing your behavior as well. You do not have to answer incriminating questions like “How much have you had to drink tonight?” It’s usually safest to politely decline to answer or say you’d rather not say. Remember that at this stage the officer is gathering evidence; you are not going to talk your way out of a DUI if you indeed are impaired, so saying anything beyond basic identifying information often does more harm than good.
Know Your Rights During a DUI Stop
Being pulled over on suspicion of DUI can be intimidating, but you still have legal rights in this situation. Two key rights to remember are: the right to remain silent and the right to legal counsel.
If you are stopped or arrested for suspicion of DUI, you have the right to remain silent – in other words, you do not have to answer investigative questions about drinking or where you’re coming from. You must provide your driver’s license, registration, and proof of insurance when asked, and you should comply with orders to step out of the vehicle. But you do not have to participate in a roadside interrogation. It’s usually wise to be polite but firm in not answering questions that go beyond basic identification. For example, you can politely say, “Officer, I choose not to answer any further questions until I have a lawyer present.” According to legal experts, asserting your right to silence cannot be used against you in court – it’s your constitutional right.
You also have the right to speak to an attorney as soon as possible if you’re detained. In Canada, upon arrest, police must inform you of your right to counsel and give you a chance to call a lawyer. In Ontario, you can speak to a free duty counsel lawyer if you don’t have one. It’s highly recommended to take advantage of this right – a lawyer can advise you on what to do (for instance, whether to provide a breath sample or not, given the circumstances). Keep in mind, if you refuse the breathalyzer after being arrested without a valid legal reason, you will face serious consequences (license suspension, criminal charges for refusal, etc.), so legal advice in that moment can be crucial.
Another important concept is implied consent laws. When you drive, you’ve implicitly agreed to undergo chemical tests (breath or blood tests) if lawfully arrested for DUI. In many jurisdictions, refusing an official breath test after arrest is itself an offense that carries penalties. For example, under Ontario’s laws and Canadian Criminal Code, refusing a required breath test will trigger an immediate 90-day license suspension and other administrative penalties, just like a DUI charge. In fact, even if you’re ultimately not convicted of impaired driving, the license suspension for refusing can still apply. In short, refusal is not an easy escape – it can hurt your case. The general advice from lawyers is to comply with the breath test requirement once you’re under arrest, since the consequences of refusal are comparable to (or in some ways worse than) a first-time DUI conviction.
Bottom line: During a DUI stop, cooperate with the officer’s basic instructions (pulling over, exiting the car, providing ID, etc.), but remember you don’t have to volunteer information that might incriminate you. You have the right to remain silent about where you were, what you drank, or how you feel. You also have the right to consult a lawyer, usually right after any arrest is made or even before a formal arrest if possible. Exercising these rights can never be held against you, whereas waiving them could unintentionally strengthen the case against you.
From Suspicion to Charge: What Happens Next?
If the officer’s suspicion of DUI is confirmed by evidence (such as failing field tests or a breathalyzer reading over the legal limit), you will be charged with a DUI offense. In Toronto and across Canada, this charge is typically called “Impaired Driving”, “Driving Over 80” (if over 0.08% BAC), or “Refusal to Comply” (if you refused tests). Being charged means you’ll likely spend some time in custody (often until you sober up or for a few hours) and then be released with a court date.
It may come as a surprise, but even before you ever see a courtroom, Ontario imposes swift penalties at the charge stage. Upon being charged (or even issued a roadside license suspension for a fail or refusal), you will face: an immediate 90-day driver’s license suspension, a 7-day vehicle impoundment, and an administrative monetary penalty (around $550 in Ontario) plus a $281 license reinstatement fee. These consequences kick in right away, long before any finding of guilt, under Ontario’s Administrative Driver’s License Suspension (ADLS) program. The goal is to promptly get potentially dangerous drivers off the road. So, being arrested on suspicion of DUI has very real and immediate ramifications: you’ll be walking or finding rides for the next few months as your license will be gone.
If the charge proceeds to court and you are convicted of DUI, the penalties become even more serious. Under Canada’s criminal law, even a first-time impaired driving conviction carries a mandatory $1,000 fine and a one-year driving prohibition at minimum, plus the possibility of jail (up to 10 years maximum for a basic DUI). In addition, you would have a criminal record. Subsequent offenses lead to mandatory jail time (at least 30 days for a second offense, 120 days for a third) and longer driving prohibitions. There are also provincial consequences like required alcohol education programs and ignition interlock device requirements once you get your license back. In short, a DUI conviction can derail your life – fines, lost driving privileges, increased insurance costs, potential job impacts, and even immigration/travel issues (since Canada treats DUI as a serious crime).
The good news (if any) is that suspicion of DUI does not guarantee a conviction. There are many defenses a skilled lawyer can explore: Was the traffic stop legal? Were the tests administered properly? Could medical conditions have affected the results? Are the devices calibrated? If any reasonable doubt is raised in court, the DUI charge could be reduced or dismissed. That’s why if you’re arrested on suspicion of DUI, it’s wise to consult an experienced DUI defense lawyer as soon as possible. They can review the case for weaknesses (for example, if the officer lacked proper grounds or made procedure errors) and defend your rights vigorously.
Conclusion: Stay Informed and Protect Your Rights
“Suspicion of DUI” simply means an officer thinks you might be driving impaired – it’s the first step in the DUI enforcement process, not a finding of guilt. Knowing what it means and what the process looks like can help you make better decisions if you ever find yourself in this situation. If you’re pulled over on suspicion of DUI, remember to stay calm, know your rights, and comply with lawful orders. Being informed can prevent you from unintentionally making your situation worse. And if you do end up facing charges, reach out for legal help promptly – a qualified attorney can make a huge difference in navigating the aftermath of a DUI accusation.
Driving is a privilege that comes with responsibility. The best way to avoid DUI trouble is, of course, not to drive if you’ve been drinking or using impairing substances. But if a lapse in judgment happens, or if you believe you were wrongly suspected, understanding the term “suspicion of DUI” and the process around it will help you respond in the smartest way possible. Stay safe and informed – and when in doubt, call a cab or rideshare instead of taking the wheel after drinks. Your future self will thank you.