What are the elements for a backward-looking access cause of action?

In Christopher v. Harbury (2002) 536 U.S. 403, the court addressed the allegations necessary to state a claim for denial of the right to access to courts. The court distinguished between claims involving a litigating opportunity already lost (i.e., backward-looking access claims) and claims involving a litigating opportunity yet to be gained (i.e., forward-looking access claims). (Id. at pp. 414-415.) An example of a forward-looking claim is a prisoner class action to remove roadblocks to future litigation, such as an inadequate prison library. (Id. at p. 415.) The elements for a backward-looking access cause of action, which is the type plaintiff is asserting here, include (1) actual injury, (2) the official acts frustrating the litigation, and (3) a remedy that may be awarded as recompense that is not otherwise available in a future suit. (Id. at pp. 413-414.) To sufficiently plead actual injurythat is, the loss or impediment of an arguable, nonfrivolous underlying cause of actiona plaintiff must describe the underlying cause of action "well enough to apply the 'nonfrivolous' test and to show that the 'arguable' nature of the underlying claim is more than hope." (Id. at p. 416.) To adequately plead the third element, "the complaint must identify a remedy that may be awarded as recompense but not otherwise available in some suit that may yet be brought." (Id. at p. 415.)