The Guardian news and media group (GNM) is undertaking a major restructuring of its legal function following the appointment of legal director Siobhan Butterworth to the position of reader's editor in December.

The current team of seven lawyers is to be spilt into two separate divisions, which will take care of the group's commercial and editorial interests respectively. Butterworth's role as legal director will not be filled when she steps down in April.

Sarah Davis – who joined The Guardian as a commercial lawyer in 2000 and was formerly legal counsel at technology company NDS – will head up the commercial legal team, reporting to GNM managing director Tim Brooks.

Nuala Cosgrove, legal manager at The Guardian and former intellectual property counsel at Burberry, will take charge of the editorial legal team and will report to editor Alan Rusbridger.

Davis and Cosgrove both trained at City firm Finers Stephens Innocent and will each see the numbers in their teams boosted, with one new recruit set to join the editorial team and the commercial group expected to grow by two.

Brooks said: "The creation of these two new divisions and our increased investment in legal services recognises the value we place in this area of work. We are fortunate to be able to draw on the talent and expertise of Nuala and Sarah to drive these two divisions forward."