What is the test for an inmate to have access to the courts?

Prisoners have a fundamental constitutional right of access to the courts. Lewis v. Casey, 518 U.S. 343, 346 (1996). This right is essentially limited to direct criminal appeals, habeas petitions and civil rights actions pursuant to 42 U.S.C. 1983. Id., at 354. To establish a violation of his constitutional right to court access, plaintiff must show an "actual injury." Id., at 349. The high court held that before a denial of access to the courts claim can go forward, an inmate must "demonstrate that a nonfrivolous legal claim had been frustrated or was being impeded." Id., at 351-53, 355.