Shirley Schmidt (played by Candice Bergen) is the no-nonsense third named partner at Crane, Poole & Schmidt. Shirley returned to the Boston office in episode 1x11 [Schmidt Happens], having spent the previous three years in New York. Upon seeing her, Denny Crane told Brad Chase that he and Shirley had once had an affair. It's not clear if this is why she had moved away from Boston, but Denny was initially very upset about her return. Later, it became evident that Denny still has some affections for her.

Shirley attended Wellesley College (2x18 [Shock And Oww!]). According to a diploma spotted in Shirley's office on the set (see reference below), she graduated in 1966 with a degree in Political Science. However, this doesn't match up with the story she told to Alan Shore (also in Shock And Oww!) that she was a sophomore in the summer of 1966. Another diploma seen on the set shows that she received the degree of Juris Doctor from Harvard Law in 1970.

Shirley has been married at least once, for four years, to Ivan Tiggs, with whom she also practiced law for a time (2x16 [Live Big]). It's not clear if she's been married any other time, but she stated in Shock And Oww! that she has grandchildren, implying that she has at least one child. She and Ivan have never discussed any children of theirs. Little is known of anybody else in Shirley's family except that her father suffers from Alzheimer's disease and resides in a nearby care facility (2x08 [Ass Fat Jungle]).

Shirley seems unashamed when it comes to having affairs with married men. Her past married lovers include photographer Karl Hauser (also in Shock And Oww!), Judge Simon Devon (2x27 [BL: Los Angeles], and Ivan Tiggs (while he was married to Missy). It's not clear whether Shirley and Denny's affair took place during one of his first five marriages. Shirley also had at least one sexual encounter with Jeffrey Coho (3x02 [New Kids On The Block]).

Reference:
Walking Tour of the Boston Legal Sound Stages (MANY thanks to Crabby from www.boston-legal.org for this wonderful write-up)