San Francisco-based Gordon & Rees is set to open an office in Philadelphia on Friday with eight partners from Cozen O’Connor’s insurance and commercial litigation teams.

Gordon & Rees has hired away three senior members of Cozen O’Connor’s insurance and commercial litigation groups. William Shelley, the former chairman of Cozen O’Connor’s insurance group, and partners Ann Thornton Field and Josh Wall will join the new firm along with Cozen O’Connor partners Joseph A. Arnold, Jacob C. Cohn, C. Tyler Havey, James E. Robinson and Catherine Slavin.

Cozen O’Connor’s Houston office leader, Joseph Ziemianski, will now move from vice-chairman of the firm’s global insurance practice to chairman of the practice.

Cozen O’Connor Chief Executive Officer Michael Heller said he wasn’t sure about whether associates would be moving, but said he anticipates between nine to 12 Cozen O’Connor attorneys would be leaving the firm for Gordon & Rees.

“They were terrific lawyers and terrific people who in the past have been very, very actively involved in management of the firm,” Heller said of the trio that has left. “Over the past several years we have really broadened the lateral recruiting in the insurance and commercial litigation space [and have] diversified our management and brought others into management. So my instinct is they felt it was a good opportunity for them to really go back into managing their own practices … individually as opposed to not having as big of a management role at the firm as they once had.”

Field had served in a number of leadership roles during her time at Cozen O’Connor. She was vice chair of the commercial litigation group, a member of the management committee and a member of the board of directors. Her practice is focused on general litigation, aviation and products liability matters.

Wall had been with Cozen O’Connor since 1977 and was a member of the firm’s global insurance group. He represents clients involved in property, casualty and insurance litigation matters.

Aside from serving as chairman of Cozen O’Connor’s global insurance group at the time of his departure, Shelley was also on the firm’s board of directors and management committee. He was responsible for the management of the 125 attorneys and paralegals in the department. His practice focuses on insurance coverage issues, including general and professional liability.

“Whenever you lose senior people that you like, it’s always a loss,” Heller said of losing the three attorneys.

But he said Cozen O’Connor was committed to continued expansion of the insurance practice. He said the firm has a very unique mix of practices and the insurance group has been a big contributor to the firm’s financial success over the years. He said Cozen O’Connor will continue to “aggressively expand” the practice.

This isn’t the first time Gordon & Rees has raided a Pennsylvania firm to open an office in the state. The firm opened in Pittsburgh in March 2012 with the hire of seven attorneys from Buchanan Ingersoll & Rooney. That team was led by partner S. Manoj Jegasothy, who now serves as managing partner of the Pittsburgh office. That office now has 13 attorneys.