The governing body intervened because Six Nations chiefs opted not to sanction Marler despite him admitting to an offence that typically carries a minimum suspension of four weeks.
Marler, who is free to play for Harlequins until his hearing at an as-yet unspecified date, made the controversial remarks during the first half of England’s 25-21 win over Wales two weeks ago.
“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,” it said.
“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 (the player’s union) and Six Nations Rugby have been informed and the case will be heard by an independent judicial committee as soon as practically possible.”
Six Nations chiefs said they spared Marler punishment because he took the unusual step of apologising to Lee at half-time and his comments had been made “in the heat of the moment”.
Rugby Football Union chief executive Ian Ritchie this week insisted that he believed a reprimand was sufficient and Marler’s jibe had been “inappropriate” but not racist.
“I’ve seen the quotes from Samson Lee as to how he saw it,” Ritchie added. “I think it’s important how the recipient – if I can put it that way – receives it.”
The Wales camp appeared at odds over its reaction to the storm, with head coach Warren Gatland playing down the flashpoint as “banter”, only to have to retract that statement when it generated further ire.
The Welsh Rugby Union, by contrast, publicly expressed its surprise when Six Nations organisers confirmed they would not subject Marler to an independent disciplinary hearing.