WASHINGTON — The head of the NFL Players Association says the union is establishing an eight-member commission to advise it about domestic violence prevention and discipline.

In a letter sent Monday to Sen. Jay Rockefeller, the West Virginia Democrat who chairs the Senate Commerce Committee, NFLPA Executive Director DeMaurice Smith writes that “when these matters are left solely to the NFL, the process is mismanaged and often the end result has not been able to withstand outside review.”

Rockefeller’s committee is holding a hearing Tuesday about domestic violence in professional sports, with representatives of the NFL, NBA, NHL and Major League Baseball scheduled to testify. Officials from the basketball, hockey and baseball unions are also scheduled to appear.

Smith says “long-scheduled overseas travel prevented” the NFLPA from participating Tuesday.