NRL chief executive Dave Smith announced on Thursday Earl had made admissions about the use and trafficking of peptide CJC-1295 and other prohibited substances when interviewed by the Australian Sports Anti-Doping Authority recently.
Smith said Earl had volunteered to stand down while the charges against him were dealt with.
He said Earl has agreed to continue to assist with the ASADA investigation and is seeking to obtain the benefit of substantial assistance provisions for doing so.
Smith said the development was a clear reminder of the significance of ASADA's ongoing investigations.
ASADA's investigations have centred on the Cronulla club and its 2011 controversial supplements program but they have also been interviewing players and officials from several other clubs in the wake of the Australian Crime Commission report released in February.
"Today's development reinforces the position we have taken from the outset and highlights our resolve in dealing with what are serious issues," Smith said.
"We continue to work with ASADA...to get to the bottom of all allegations.
"We will act on evidence when it is fully available.
"Everyone should be in no doubt that ASADA is continuing its investigations and that we will continue to work closely with them.
"I stress that we do not have evidence at this stage that would warrant any further action against any individual or club.
"Our resolve on these issues remain clear.
"There is no place for drugs in our game and the sweeping actions we have taken in relation to new drug testing and the formation of the integrity unit this year underline our commitment in that area."