Joe Marler could still face punishment for calling Samson Lee "gypsy boy" in England's Six Nations victory over Wales after World Rugby confirmed the prop's comments "amount to misconduct".
Marler went unpunished for insulting Lee in England's 25-21 win, having apologised to the Welshman at half-time in the Twickenham match.
The Welsh Rugby Union (WRU) expressed surprise at the lack of punishment over the comments, which Wales coach Warren Gatland dismissed as banter before backtracking.
England coach Eddie Jones was typically bullish over the matter, accusing the WRU of trying to unsettle his side's ultimately successful attempts to round off the Grand Slam against France last weekend - a game that Marler was benched for.
Marler remains free to play for Harlequins while the proceedings are ongoing, but a suspension may loom after World Rugby confirmed they adjudged his behaviour to have contravened the laws of the game.
A statement read: "World Rugby is of the view that the comments amount to misconduct and/or a breach of the code of conduct under World Rugby Regulation 20 and should have been considered by an independent process.
"In the absence of such a process by Six Nations Rugby, World Rugby is exercising its right to take appropriate action before an independent judicial committee.
"The RFU [Rugby Football Union] and Six Nations Rugby have been informed and the case will be heard by an independent judicial committee as soon as practically possible."