A girl with a conflicted past, Coates came from an unhappy home with a very strict and unforgiving father; it was implied her father was physically abusive to her. Originally a client of Rabb's and an Electronics technician (United States Navy) on the USS Gainsville, she was accused of abandoning her position, for which she was up for court martial. After spending a Christmas Day with the JAG officers.[1] Coates decided to "straighten up." She served her time in the brig, then changed her rating to that of a legalman. She was assigned to the USS Seahawk shortly before LT Roberts was assigned to the ship as JAG officer.[2] She was later reassigned to JAG Headquarters, continuing as a legalman and as Admiral Chegwidden's personal assistant. She became a valued member of the team. One of her old "friends" nearly framed her for murder before Harm and the D.C. police proved she was innocent.

When Harm becomes the foster dad to Mattie Grace, and needs a larger apartment for them to live in, he persuades Coates to move into the two-bedroom apartment next door so that Mattie can live there with her. (Coates had difficulties with her 4-5 female roommates; Harm inveigled Coates to be Mattie's roommate by paying Mattie's expenses – though his original offer was to pay all costs for both Coates and Mattie). Harm wanted Coates for Mattie's roommate as he felt that Mattie, being a teenager, would need a female role model.

Coates was initially a Petty Officer Third Class and was promoted to Petty Officer 1st Class in 2004.

Coates was portrayed by Mclellan, Zoe.