Crimes and Tickets

Drinking, Drugs and Driving: Arrest and Tests


Police officers can ask drivers to give a breath sample or do physical coordination or other tests to see if their ability to drive is affected by alcohol or drugs. This article explains what the police can do with drivers who are not fit to drive.

Police can stop drivers who are unfit to drive.

Police officers on patrol can stop you if you have difficulty controlling your car, for example, you’re not driving straight, can’t stay in your lane, break suddenly for no reason, drive too fast or too slowly or get into an accident.

During random checks, police officers can check your driver’s license and registration papers. At the same time, they can check whether you’re fit to drive. Police can also put up roadblocks to check whether you’ve taken alcohol or drugs and to test your ability to drive.

You must stop if a uniformed police officer asks you to, no matter the circumstances. The police officer can question you about your car, your driving and whether you’ve taken any drugs or alcohol.

Tests when drivers are stopped

Tests using approved screening devices

If a police officer stops you, the officer can ask you to give a breath sample using an approved screening device to detect the presence of alcohol in your blood. It uses a sample of your breath to determine your approximate blood-alcohol level.

A police officer who suspects you’ve used drugs can ask you to do a test using an approved screening device for drugs. It uses a sample of your saliva to estimate the amount of drugs in your blood.

These preliminary tests give only an approximate measure of drugs or alcohol and can’t usually be used in court. But they can give a police officer a good reason to ask you to take a more accurate test at a police station.

Physical coordination tests

Police officers can also ask you to do physical coordination tests if they suspect you’ve taken drugs or alcohol.

For example, they can ask you to walk in a straight line, turn or stand on one foot while counting out loud without losing balance.

They can ask you to do physical coordination tests only or in addition to the tests using approved screening devices.

In addition, police officers can observe you while talking with you and make notes on anything that shows you’re unfit to drive. Here are examples:

  • strong smell of alcohol on your breath
  • red or glassy eyes
  • slurred or difficult speech
  • loss of balance for no reason
  • incoherence, confusion and mood swings

Drivers’ rights and responsibilities

Police officers must ask you to do the screening tests as soon as possible after stopping you. You have a right to know whether they will arrest you.

If asked by a police officer, you must:

  • show your driver’s licence, registration certificate and proof of insurance,
  • blow into an approved screening device to test for alcohol or give a saliva sample to test for drugs, and
  • do physical coordination tests if asked.

Important! Refusing to do these tests without good reason is a crime. The punishment is usually the same as for impaired driving or driving with more than the legal limit of alcohol or drugs in your blood.

Police officers can question you, but you have the right to remain silent.

The two-hour rule

In some cases, you can be charged with impaired driving for up to two hours after you stop driving. For example, imagine you leave the bar after having a few drinks and get in an accident. Instead of stopping, you decide to go home. The police can show up and may demand a breath sample within 2 hours.  If their investigation reveals that you are over the legal limit, then you could be charged with impaired driving. 

The same rule also applies to impairment driving due to drugs.

Consequences of failing initial screening tests

The results of the tests and observations might give police officers reasonable grounds to arrest you for impaired driving or driving with more than the legal limit of alcohol or drugs in your blood.

If arrested, you have the right to speak to a lawyer.

The police officers may do these things:

  • order you to do more precise tests at a police station
  • take away your driver’s license
  • seize your vehicle

Refusing to go to the police station for further tests is also a crime.

If arrested, you have the right to remain silent but you must give your name, address and other information to confirm your identity.

For more information, read our article Rights During a Detention or Arrest.

Tests at a police station

At the police station, you might be asked to do other tests to measure the exact amount of alcohol or drugs in your blood.

Breath sample test

The breath sample test involves taking a breath sample to measure the level of alcohol in your blood. It is more precise than the preliminary breath test using an approved screening device. If the result shows a blood-alcohol level over the legal limit (.08), it can be used as proof that you committed a crime. A qualified technician, who can be a police officer, gives the test.

Contesting the results of the breath sample test

The breath test is approved by the government and is usually reliable. But the machine can malfunction and give a wrong result.

To contest the results of a breath sample test, you must show that the device was not used or did not work properly. It’s a good idea to consult a lawyer.

Blood sample test

You can be ordered to give a blood sample if your physical condition at the time of arrest makes it difficult or impossible to give a breath sample.

For example, someone with asthma or a mouth or jaw injury might not be able to blow hard enough in the device to get a reliable breath sample. The police officer can then order the driver to go to the hospital to give a blood sample.

Tests for drugs

Police officers can order more advanced tests if the tests at the police station give them reason to think your ability to drive is impaired by drugs or a combination of drugs and alcohol.

They can order you to give a blood sample to test the amount of drugs in your blood. The blood sample must be taken by a doctor or qualified technician.

They can also order tests done by a qualified officer (evaluating officer). The evaluating officer can do a series of physical exams, such as taking your pulse or temperature, examining your pupils or asking you to follow an object with your eyes. This officer can also order you to give a saliva, urine or blood sample or do a breath sample test if you haven’t done one already.

After the tests, you might be formally accused of a crime. If found guilty, you’ll receive a sentence that can have serious consequences on your life. To learn more, read our article on the consequences of driving under the influence of drugs or alcohol.