The state opposition has warned of a "law and order auction" after the Baird government axed the department of the Attorney-General and brought it under the control of the police minister.

Under a shake-up of departments by new Premier Mike Baird, announced on Wednesday, the Department of Attorney-General and Justice has been replaced with the Department of Police and Justice.

The department is headed by Police Minister Mike Gallacher, who is more senior in the hierarchy of ministers than new Attorney-General Brad Hazzard, formerly the planning minister.

"This suggests the Attorney-General is subservient to the Minister for Police," shadow attorney-general Paul Lynch said.

"Before the last election this government promised to stop the law and order auction. This decision is the latest of several to demonstrate that that decision was completely hollow."