implicitly recognized a constitutional cause of action based on the widow’s allegations of "arbitrary government action” — allegations apparently lacking in Johnson — when it ”refus[ed] to characterize the city’s alleged [failure to train or warn] in this case as arbitrary in a constitutional sense.” Id. at 128, 112 S.Ct. 1061 (emphasis added). We have no reason to believe the Court in Collins limited such cause of action to the employment context. In fact, the Court noted that the employment relationship was "not of controlling significance” and that its analysis would apply to "pedestrians” harmed by a city’s deliberate indifference to his or her safety. Id. at 119, 112 S.Ct. 1061; see also County of Sacramento v. Lewis, 523 U.S. 833, 836, 118 S.Ct. 1708, 140 L.Ed.2d 1043 (1998) (<HOLDING>). Today, however, we need not address the
holding that plaintiff must allege conduct so arbitrary and unreasonable that it shocks the conscience in order to state substantive due process claim in context of social workers alleged interference with parents custody rights recognizing  1983 substantive due process claim holding that the passenger of a vehicle being pursued by police was not seized during a fatal collision and therefore could assert a substantive due process claim under the fourteenth amendment holding a police chase of a fleeing suspect that resulted in a fatal accident may support a substantive due process claim based on the theory that the officers conduct constituted arbitrary government action shocking the judicial conscience recognizing that substantive due process tenet which ensures that government action is not arbitrary regardless of whether the procedures afforded were fair