Where a rule of decisional law is enunciated as an application of previously existing principle, must it be applied in all open cases?

Where a rule of decisional law is enunciated as an application of a previously existing principle, it must be applied in all open cases. [63 Cal.App.3d 957] (People v. Heredia (1971) 20 Cal.App.3d 194, 199, 97 Cal.Rptr. 488.) Where a new rule of law is stated, however, the retroactivity of a decision must be established by the court faced with the application of that ruling. That part of Duran which holds that restraints may not be imposed in the absence of a manifest need for such restraints is an application of the rule established in People v. Harrington (1871) 42 Cal. 165. However, that portion of Duran which holds that there must be a record showing of the need for restraints enunciates a new rule of law.