Source: Canadian Tort Law in a Nutshell, 4 ed. p. 66 Bottom
Not every error made by a professional, amounts to negligence. The law does distinguish between incompetence and mere "errors in judgment." An error falls into the latter category if it is the kind of error a competent professional might make.34 This appears to be an objective standard which is subjectively applied, as there are no clear criteria from the cases indicating how errors of judgment are to be identified.
34Lapointe c. Hôpital Gardeur (1992), 90 D.L.R. (4th) 7, 1992 CarswellQue 47, 1992 CarswellQue 131, 10 C.C.L.T. (2d) 101, [19921 1 S.C.R. 351, 9 C.P.C. (3d) 78, (sub nom. Lapointe v. Chevrette) 133 N.R. 1 16, (sub nom. Lapointe v. Chevrette) 45 Q.A.C. 262,  S.C.J. No. 11 (S.C.C.); Pelky v. Hudson Bay Insurance Co. (1981), 35 O.R. (2d) 97, 1981 CarswellOnt 706,  1.L.R. 1-1493
How exactly would an objective standard (henceforth OS) be applied subjectively? How does subjective application differ from objective application of an OS?