What are the implications of the First Amendment right of an inmate to file a grievance?

"Of fundamental import to prisoners are their First Amendment rights to file prison grievances, and to pursue civil rights litigation in the courts. Without those bedrock constitutional guarantees, inmates would be left with no viable mechanism to remedy prison injustices. And because purely retaliatory actions taken against a prisoner for having exercised those rights necessarily undermine those protections, such actions violate the Constitution quite apart from any underlying misconduct they are designed to shield." Rhodes v. Robinson, 408 F.3d 559, 567 (citations, internal quotations and footnote omitted) (9th Cir. 2005).