What is the standard for determining whether a public employee is discretionary and therefore entitled to immunity under section 820.2?

The standard for determining whether the act of a public employee is discretionary and therefore entitled to immunity under section 820.2 was set forth in Johnson v. State of California (1968) 69 Cal.2d 782, 794-795, fn. 8, 73 Cal.Rptr. 240, 447 P.2d 352.) "[T]o be entitled to immunity [217 Cal.App.3d 313] the state must make a showing that such a policy decision, consciously balancing risks and advantages, took place. The fact that an employee normally engages in 'discretionary activity' is irrelevant if, in a given case, the employee did not render a considered decision." (Ibid.)