Paul Williams joined New Zealand's high-performance squad in 2014, which thrust him on to the Mitre10 Cup stage. A former player, Williams has a sound tactical knowledge and took up refereeing at a junior level in 2011 while still playing scrumhalf for Southern. He joined the Super Rugby panel for the 2016 season and refereed 5 matches in his debut year and followed this up with 6 matches in 2017. In June of 2018 he took charge of the second test between Australia and Ireland in Melbourne and added two more tests, England vs Japan and Scotland vs Argentina during November of that year.  In 2019 he had a busy Super Rugby schedule as well making his 6 Nations debut when England host Scotland at Twickenham Stadium on the 16th March. In 2020 he will establish himself as a core Super Rugby referee and will further his international experience when he referees Scotland v France in the 2020 Six Nations.