John Hession, a corporate lawyer who will be 64 in November, helped establish Cooley’s Boston office in 2007, as a partner. But when he talked with the firm at the end of last year about his wish to keep working as counsel past Cooley’s mandatory retirement date of 65, the firm balked.

So he picked up the phone and called a headhunter, and by February he had joined Morse, Barnes-Brown & Pendleton, a much smaller firm, as an equity partner. He is helping to build the firm’s corporate practice in biotech and technology.