Introduced in 1902, it prohibited GAA members, under pain of suspension, from playing, attending or promoting soccer, rugby, hockey and cricket, which were commonly referred to as 'foreign games'.
It was strictly applied, even to the point of removing Dr Douglas Hyde as GAA patron in 1938 because he attended an international rugby match in his role as President of Ireland. In 1963, famous Waterford hurler Tom Cheasty was suspended for attending a dance run by a soccer club. Down star Paddy Doherty was another high-profile casualty, suspended for playing soccer.
It was a deeply divisive rule and the Cheasty suspension in particular raised levels of unease to such a degree that, in a rapidly changing Ireland, it was only a matter of time before Rule 27 was abolished. It happened in 1971 when 'The Ban' was deleted at Congress in Belfast without the expected dissent. Antrim registered their support for the rule but did not formally oppose its abolition and, in a matter of minutes, possibly the most restrictive regulation in GAA history was gone.
It prevented members of the British armed forces and police from joining the GAA. It was unlikely there was going to be a stampede of British soldiers or RUC officers to join the GAA even if the rules allowed it but for decades the GAA held the restriction as an important part of its national identity. Harassment of GAA members by the security forces, plus the provocative occupation of part of Crossmaglen Rangers' grounds by the British army, were regarded as good reasons to retain the ban but the landscape changed in the 1990, thanks to the emerging peace process.
The establishment of the PSNI -- complete with many recruits from the Nationalist/Catholic community -- also meant that if the rule was retained, the GAA would be in a very awkward position. Joe McDonagh took the first steps towards having it removed during his presidency but it was his successor, Sean McCague, who presided over its deletion at a Special Congress in November 2001.
It prevented the use of GAA property for "horse racing, greyhound racing or for field games other than those sanctioned by Central Council".
Its main targets were soccer and, to a lesser extent, rugby. It shot up the agenda following the redevelopment of Croke Park in the 1990s and the failure of the government to deliver a national stadium as promised. With Lansdowne Road deteriorating to a stage where it had to be completely redeveloped, pressure grew on the GAA to open Croke Park so as to prevent the embarrassment of playing Ireland's rugby and soccer 'home' games in Britain.
The debate was hugely divisive. In 2001, a proposal to Congress to amend Rule 42 in relation to Croke Park lost by just two votes amid controversy as to how the show of hands was counted. The debate continued over the next few years and the rule was finally changed in 2005 during Sean Kelly's presidency. It was carried on a 227-97 vote and the first international rugby game was played in 2007 when Ireland lost to France in the Six Nations.
"The Association is an amateur Association. A player, team, official or member shall not accept payment in cash, or in kind, in conjunction with the playing of Gaelic games. A player, team, official or member shall not contract himself/itself to any agent other than those officially approved by Central Council. Expenses paid to all officials, players and members shall not exceed the standard rates laid down by the Central Council. Members of the Association shall not participate in full-time training. This rule shall not prohibit the payment of salaries or wages to members of the Association."
This is the rule which the GAA claim is being broken through illegal payment to managers. There are other elements of the rule open to query too but, for now, payments to managers is the only concern in Croke Park.