Impaired driving does not mean intoxication. Impaired driving means that the ability to operate a motor vehicle was impaired due to the consumption of an alcohol or drug.
Where a person is found operating a motor vehicle and their blood/alcohol level is over 80mgs the police will arrest and lay a charge of drive over 80mgs.
Police can only demand a breathalyzer test under certain conditions. The police have a legal responsibility to ensure that the driver understand their obligation.
Dangerous driving is not carelessness. The incident or driver action must be something that was not an accident or error in driving, but an action that was done with intent.