Rugby Union's law book extends to almost 150 pages, but the sport's governing body is keen to simplify things.

The IRB has been trialling a series of experimental laws at Stellenbosch University in South Africa.

Former Test match referee Paddy O'Brien - now the IRB's referee manager - is one of the brains behind the changes, along with former international coaches Rod Macqueen, Ian MacIntosh, Richie Dixon and Pierre Villepreux.

BBC Sport spoke to O'Brien about some of the key changes, and how they could affect the sport.