King & Spalding's Robert Hays.

Robert Hays has been re-elected to an unprecedented fifth term as chairman of King & Spalding by the Atlanta-based firm's partnership. His new three-year term will start Jan. 1.

Since Hays became the firm's leader in 2006, King & Spalding has expanded markedly in size and revenue, rising to No. 27 in the Am Law 100 rankings of highest-grossing U.S. law firms. The firm was ranked No. 42 in 2005, the year before Hays assumed leadership.

It has opened 15 new offices, including locations in Tokyo, Los Angeles and, most recently, Chicago, during Hays' current term. It now has 21 offices altogether.

The firm's revenue has almost doubled since 2006, from $582 million to $1.058 billion in 2016. Profit per partner jumped from $1.3 million to $2.5 million during that period.

Last year King & Spalding broke the 1,000 lawyer mark in head count after passing the $1 billion mark in revenue in 2015.

Hays started out at King & Spalding as a trial lawyer and led its tort and environmental litigation practice for 12 years—a key practice for the firm—before becoming chairman. He's been a member of the firm's policy committee, as its governance group is called, for 18 years. (Hays' brother, Richard Hays, has been chairman of rival Atlanta firm Alston & Bird since 2008.)

“It is a privilege to have been chosen again to lead King & Spalding into its next chapter,” Hays said in a statement. “We have enjoyed strong growth and success thanks to the dedication and drive of our passionate team of lawyers and staff.”

“One of our core qualities is our belief that we can do better, so I'm excited by the chance to continue working with everyone across the firm to help us evolve even further,” he said.