Sherman & Howard, Denver’s oldest and third-largest law firm, is merging with Taft, a law firm that started in Cincinnati and is expanding west. Stefan Stein, CEO of Sherman & Howard, said in an interview Monday that the Denver firm had been exploring strategies for growth over the past couple of years. “It’s a difficult spot to be in the market in a 125-to-a-150-lawyer, full-service law firm and be able to handle virtually anything that comes in the door,” Stein said.