The Approved Screening Device

Much has been written recently about the Approved Screening Device being used by police to test drivers under the Immediate Roadside Prohibition program. Many are curious about how it works, and those that have been tested were quite often surprised at the result. The authority for the screening comes from section 254 of the Criminal Code.
Where a peace officer reasonably suspects that a person who is operating or has care and control of a motor vehicle, vessel or aircraft, or is assisting in the operation of an aircraft, whether it is in motion or not, has alcohol in his body, the peace officer may demand that the person provide a proper sample of breath to be analyzed in the roadside screening device. The peace officer may also demand that the person accompany him to enable the sample to be taken.
Every one commits an offence who, without reasonable excuse, fails or refuses to comply with the demand made to him by a peace officer. The courts have held that it is a reasonable restriction on a persons rights under the Charter of Rights and Freedoms that the sample be provided without being entitled to consult counsel. This means that it is not an excuse to refuse because you haven't talked to a lawyer first.
The Motor Vehicle Act leaves a police officer making a roadside breath test under the Criminal Code no discretion. Depending on whether the test results in a warn or a fail, they must take possession of the driver's license and issue the appropriate prohibition document. The requirement to prohibit also applies if the driver refuses without lawful excuse to provide a proper breath sample.
Reference Links
You may also wish to read:
Survey - Natural Resource Road Act Project