A good friend and former Naval Academy classmate of Harm, and a great rival in the courts. He served on submarines before becoming a lawyer and is the son of a Baptist Navy chaplain. Sturgis and Harm play hoops and fix cars together. He kept secret that Mac let it slip to him "That she was in love with [Harm]." He was also accused of incompetence in a case, only to be defended unsatisfactorily by Bud, causing a rift between the two. Ironically, later on, there arise two separate situations in which each defends the other successfully - when Sturgis is accused of racism against North Koreans under arrest in a US submarine, and when Bud is accused of assault when he hits an agitated and argumentative history professor under the assumption that he was about to hit his brother, Mike. Also, Sturgis went through a bout of guilt in having played a part in getting Bud into shape enough to be assigned his tour of duty as JAG on a carrier near Afghanistan, which led to the accident whereby Bud lost a leg. Aside from Harm himself, only Bud and Sturgis have noted the similarities between Mac and Diane Schonke, a deceased Naval Academy class mate of Harm and Sturgis.

He also earned a reputation for sticking to the rules, both in the courtroom as well as in investigations, to the point of being considered sanctimonious and priggish, especially by Harm. This pattern is also seen in his brief appointment as acting JAG between the leave of Rear Admiral Chegwidden and the arrival of Major General Gordon Cresswell. This further annoys Harm, who continually berates him. This leads to great animosity between the friends, finally leading to a verbal confrontation between the two when Sturgis recommends against him in an investigation on Harm's alleged shooting down of a plane carrying an Iraqi official. Showed curiosity and support for Harm and Mac's will they/won't they relationship. In the 2003 Christmas episode (Season 9, Episode 11 "A Merry Little Christmas") Turner met singer Varese Chestnut (portrayed by Erica Gimpel), who he proceeded to date, although this seemed to only last a short while. Later in the season a What If episode (titled "What if...") showed how the lives of the main cast would have been had they made different decisions. The big change for Turner was that he was retired from the navy and was acting as his fiancée's manager, his fiancée being Varese Chestnut. In the series finale Turner and Varese decided to try to see what could be, with her moving to Georgetown and subletting Mac's apartment from her since she was (apparently) moving to San Diego.

Why Sturgis left the submarine service is never explained, although in the Season 8 episode "Empty Quiver" it is mentioned that Sturgis will never be able to return to the submarine service.