Campaigning often involves voicing concerns in the public arena. Voicing issues publicly, however, can invite legal action aimed at silencing protest. People who have published books or produced reports, leaflets, bumper stickers or posters, have written letters to their local paper about a development project, or have made public statements, have received threats of legal action and some have been sued for civil conspiracy and defamation. (For information concerning the law of defamation, including defences and remedies, see: Chapter 24*2 Defamation.)

Activists that choose to assert their rights in the courts also take a risk of incurring expensive costs orders against them if they lose. In some public interest cases it has been possible to negotiate a costs cap in the early stages of litigation.