The IRB's Independent Regulations Committee Panel have delayed their judgement over Steven Shingler's eligibility case.
Shingler, who was born in Swansea, was selected for Scotland's Six Nations squad despite featuring for Wales at Under-20 level.
The selection was officially contested and the IRB found in favour of Wales, but Scotland launched an appeal soon after.
The case was heard on Monday and the committee reserved its judgement to consider all submissions and evidence.
"The Panel comprising Peter Boyle (Chair, Ireland), Tim Gresson (New Zealand) and Giancarlo Dondi (Italy) heard submissions from the player and his agent and the Scottish and Welsh Rugby Unions at the hearing while also considering detailed written submissions from the two Unions," an IRB statement read.
"The Panel was convened after the Scottish Rugby Union requested that the IRB Regulations Committee formally consider the matter in accordance with IRB Regulation 2."
Wales beat Scotland 27-13 in their recent Six Nations clash.
