A protest letter refers to a written message expressing disagreement or disapproval of a certain issue or action. It is typically sent to someone in power or authority to raise concerns and demand change. Full definition
A coalition of groups has drafted and is distributing a sample protest letter; they have also addressed comments to specific portions of the regulations. (edweek.org)
The graver threat to Corbyn would be a repeat of the 2006 riot by MPs resigning government posts and writing protest letters which ultimately did for triple election winner Tony Blair - though the would - be insurgents lack a Gordon Brown with a great clunking fist. (totalpolitics.com)
At the time when William Booth came forth with In Darkest England and his dictum that «society needs mothering,» T. H. Huxley wrote a series of protest letters to the London Times, in which he pointed to the dangers of «blind and unhesitating obedience to unlimited authority» and showed that «mothering» adults does not contribute to their maturity and growth. (religion-online.org)