When will a court grant immunity to a petitioner who allegedly engaged in illegal activities while they were not aware of the existence of a constitutional right?

Under the first part of the Wood v. Strickland rule, the immunity defense would be unavailing to petitioners if the constitutional right allegedly infringed by them was clearly established at the time of their challenged conduct, if they knew or should have known of that right and if they knew or should have known that their conduct violated the constitutional norm.

434 U.S. at 562, 98 S.Ct. at 860.

... As a matter of law, therefore, there is no basis for rejecting the immunity defense on the ground that petitioners knew or should have known that their alleged conduct violated a constitutional right. Because they could not reasonably have been expected to be aware of a constitutional right that had not yet been declared, petitioners did not act with such disregard for the established law that their conduct "cannot reasonably be characterized as being in good faith." Wood v. Strickland, 420 U.S. at 322 (95 S.Ct. at 1001).

Id. at 565, 98 S.Ct. at 861.