The union representing West Coast miners says the law should be changed to force the former chief executive of Pike River Coal to appear before the Royal Commission.
The Engineering, Printing & Manufacturing Union says Gordon Ward played an integral role in the development and running of the mine and could provide crucial insights and evidence into the explosion.
EPMU assistant national secretary Ged O'Connell says Mr Ward's evidence could help prevent another tragedy and he owes that to the memory of the 29 men who died at Pike River.
Mr Ward has refused to appear before the Commission and cannot be compelled to as he now lives overseas.
Until recently he was with the Queensland Coal Corporation.