Rule 21 was introduced in 1897 and reflected the rise of "advanced nationalism", with the GAA and other Irish nationalist organisations founded in the Gaelic revival becoming more politicised and separatist in the build-up to the revolutionary period.
[3] It was overshadowed by the introduction in 1901 of Rule 27, commonly called "The Ban", which prohibited GAA members from playing "foreign games" like soccer and rugby union.
[4][5][6] In 1938 Douglas Hyde, recently inaugurated as first President of Ireland, was removed as Patron of the GAA after attending an Irish soccer international.
Nationalists were underrepresented in the RUC, contributing to a self-sustaining cycle of mistrust of it as unionist-biased; on the other hand, unionists saw Rule 21 as evidence of the GAA's support for republican violence.
[16] After a debate closed to the public, it rejected immediate abolition due to strong opposition from the Ulster Council, but resolved to remove it "when effective steps are taken to implement amended structures and policing arrangements envisaged in the British/Irish peace agreement".
[21] After Ronan Kerr was killed in 2011 by dissident republicans, his Beragh Red Knights GAA teammates bore his coffin before passing it to his PSNI colleagues.