The HPA issued the following statement regarding the unification of rules between the three main associations (HPA, AAP & USPA):
“Following meetings last year with the AAP and USPA, and direction from the Stewards to help to produce one set of rules, the HPA’s Rules and Regulations have been redrafted and reorganised so that they are all available in one pocket book. Various aspects have been included in the Annexes and apply where referred to in Part 1 or Part 2.
Part 1 is the ‘one set of rules’ and covers the essentials for how the game of polo should be officiated and played worldwide. Although the language and the order are different in places, the rules now align closely with those of Argentina and the USA. The highlighted rules are either new for the HPA, introduced in order to align, or those that remain different, the significant one being the 30 yard penalty 2 which remains undefended.
However, each country has different rules for certain aspects such as membership, players and their equipment, substitution, pony welfare and the conditions for tournaments, and these are always going to be slightly different. These are set out as the HPA’s Supplementary Regulations and Rules in Part 2 and these shall apply to anyone who wishes to play in the UK and Ireland.
Lord Mountbatten produced a first set of International Rules in 1939 and there have been various versions since then, with the three major Associations doggedly defending their own rules. There has been a huge effort by all involved to reach a consensus and, having achieved that, it is hoped that the wording can be brought closer together and the existing few differences removed. But, perhaps more importantly, it will make it more likely that changes to improve the game for players and spectators, and to make it easier to umpire, can be agreed and introduced worldwide”.
http://www.pololine.com/?lang=1&sec=4¬e=8396&pag=0&anoB=2016