Speaking to Lawyers Weekly today, Shine Lawyers CEO Stephen Roche said the move will make the firm complete and signals its entry into the Sydney market.

"It is really exciting. It is the missing piece of the jigsaw for us. We're a firm that has called itself a national firm, but we didn't have a presence in NSW," he said.

The merge will mark the beginning of a new chapter for Shine, which has also recently teamed up with US celebrity lawyer and legal crusader Erin Brockovitch.

"We have identified there's a need for a firm like ours in Sydney, that isn't afraid to take on the tough cases," he said.

"Erin has been receiving a lot of contact from people in New South Wales, so it was time for us to answer the call."

Roche said the decision to team up with Sommerville & Co was made on the bases of quality and culture.

"[Sommerville & Co] are a great cultural fit to our organisation and that is first and foremost what we look at," he said.

"Also, they've got the most number of accredited specialists in NSW and they have a great reputation. They are a quality and professional outfit."

For the short term, Roche said there won't be too many changes in Sommerville & Co's day to day operations, while Shine gets its head around the unfamiliar personal injury laws of NSW.

"We will brand the firm Shine Lawyers in time, and there are lots of systems that will need to be assimilated, but at the present time it is business as usual," said Roche.