What is the difference between impaired driver and impaired driver?

In Kim v. ICBC, (1991) B.C.S.C., it was held that “there is a wide difference between being likely to drive improperly and being incapable of driving properly. Every driver who is under the influence of liquor to the point of being incapable of proper control is certainly impaired, but in my opinion it does not follow that every impaired driver is necessarily incapable of proper control. …but the terms of condition no. 5 does not serve to relieve an insurer from liability unless and until it has been proven by a preponderance of evidence that the insured was under the influence of intoxicating liquor to the point of being incapable of the proper control of the automobile…it would be necessary for the defendant to prove that the plaintiff’s state went beyond impairment to a point where he was incapable of driving properly. It necessarily follows that the state of incapacity cannot be established by mere proof that the breathalyzer reading exceeded point eight….”