The terms of reference of the upcoming missing women inquiry will be expanded to include a study commission, B.C. Attorney General Barry Penner announced today.

The decision follows a request from commissioner Wally Oppal earlier this month for a joint study and hearing commission.

Study commissions allow for public submissions from groups without legal standing. The commission has so far granted standing to four groups, and is reviewing other applications.

The terms of reference for the hearing commission are to examine police investigations conducted between Jan. 23, 1997 and Feb. 5, 2002 into women reported missing from the Downtown Eastside, and to review a January 1998 decision to stay charges against Robert Pickton after a sex trade worker was assaulted.

Groups representing women in the Downtown Eastside have criticized the process, calling the scope of the inquiry too narrow.

Formal hearings will take place in Vancouver later this year, and a final report is due by the end of 2011.