Whether or not the police are allowed to arrest you without demanding a roadside breath sample, depends on whether you are exhibiting signs that your ability to operate a motor vehicle is impaired by alcohol. If the police have reasonable and probable grounds to arrest a person for impaired driving, they do not have to demand roadside screening device breath sample (i.e. an ‘alcotest’) and are allowed to arrest the person for impaired driving.
If the police merely have a suspicion that a person has been drinking (for example the driver admits they have been drinking or they have an odour of alcohol on their breath and there are minimal or no other symptoms of impairment), then the police must do a roadside breath sample screening test on the alcotest before deciding to arrest.
If the person passes the screening test, there will be no criminal charges laid and the person is free to go on their way. If they blow a warning on the screening test (50 mg % to less than 100 mg %), then the person will receive a three day administrative licence suspension and their vehicle will usually be towed away, but they will not be charged with ‘over 80.’ However, If they fail the screening test (i.e. they register 100 mg %or higher on the alcotest device) the police will then arrest them for ‘over 80’ (which is a different type of charge than ‘impaired driving’) and transport them to the police station for the two “real” breath tests on an Intoxilzer.
If they pass the Intoxilyzer tests at the police station (i.e. one of the two breath sample readings is exactly 80 mg %or less), they generally will not be charged with a DUI (although there could be rare exceptions-for example if the person started to exhibit more significant alcohol impairment symptoms shortly after the screening device test, some police might charge them with impaired driving).
The police will generally round down the two Intoxilyzer reading to the nearest ten. For example, if the person’s Intoxilyzer test results were 85 mg % and 88 mg %these two readings would be rounded down to 80 mg % and the police would likely not lay an ‘over 80’ charge as the person’s blood alcohol level l was not over the legal limit of 80 mg %.
A mere odour of alcohol on person’s breath or an admission that they have been drinking, does not prove that their ability to operate a motor vehicle is impaired by alcohol. It simply shows that they may have alcohol in their blood stream and the police are required to do a roadside test to determine if they are over the legal limit.
The roadside screening device is calibrated to fail at 100 mg % (and not at 80 mg %which is the legal blood alcohol limit) to give a driver the benefit of the doubt. The results of a roadside screening device test have no evidentiary value in court, other than the fact that if a person registers a fail on an alcotest, this allows the police to arrest the person for ‘over 80’ and to demand breath samples be provided into an Intoxilyzer on two occasions at the police station. In other words, a judge at a trial is not allowed to take into account the results of the roadside screening test other than noting that it gave the arresting officer grounds to arrest for ‘over 80.’
If a police officer arrests a person for impaired driving without doing a screening test, a DUI lawyer will carefully examine the police reports (i.e. disclosure) to determine if the police had sufficient reasonable and probable grounds for arrest. If there were not sufficient objective reasonable and probable grounds for arrest, the lawyer will serve and file detailed written materials at least 30 days before the trial which is called a Charter application under s. 8 of the Canadian Charter of Rights and Freedoms, to exclude the breath samples under 24(2) of the Charter. The judge at trial will then make a decision to determine whether the breath samples should be thrown out (i.e. ‘excluded’ from evidence) based on a lack of reasonable and probable grounds.
If the judge rules on the Charter application that the breath samples should be thrown out, then the accused will usually win their case (except perhaps in those rare cases where they started to develop significant symptoms of alcohol impairment shortly after the screening device test-in that situation the crown could try and proceed on an impaired driving charge if the police laid an impaired charge. However, the crown might have a difficult time proving the person’s ability to drive was impaired beyond a reasonable doubt at the time of driving).
Filing a s. 8 and 24(2) Charter application is a common way of defending an ‘over 80’ charge. Every factual situation is unique and has to be carefully analyzed by a lawyer who is experienced and knowledgeable in defending DUI charges.