World Rugby has pledged to clarify rules on player eligibility after an independent appeal body upheld a decision to punish three countries for breaching rules during European qualification for the 2019 Rugby World Cup.
Belgium, Romania and Spain were fined and docked points after fielding players who were either ineligible or already signed up by another union.
Spain and Romania appealed against the sanctions, which had meant Russia gained automatic qualification for the 2019 tournament in Japan at Romania's expense.
Spain, who used players who had previously represented France Under-20 teams, argued their match against Belgium - refereed by a Romanian - should be replayed. Spain lost the game and failed to qualify for the World Cup.
But an independent appeal committee has upheld all the rulings and backed the punishments meted out.
It said the independent disputes committee "followed the correct approach in imposing a points deduction that was consistent with the decisions of numerous panels in different tournaments and leagues within the game".
It also said that in view of the legitimacy of those deductions, replaying the Belgium v Spain game "would have proved academic".
World Rugby welcomed the decisions.
"World Rugby is committed to ensuring that key learnings are actioned in partnership with unions and regional associations to enhance Regulation 8 (national team eligibility) understanding and compliance by all," it said in a statement.
World Rugby Chairman Bill Beaumont said it was important to ensure the situation was not repeated.
"While World Rugby welcomes the conclusion of the independent disputes process, it is important that the game learns from what were an unfortunate set of circumstances to prevent this from happening again," he said.