Milbourn's suit, originally filed in January 2016, is focused on the behavior of one specific officer — Sergeant Giogi Chiappo, who was her direct supervisor between 2011 and 2013.
"Although Sgt. Chiappo is a woman, she has publicly and privately stated in the workplace that she is 'harder on women officers' in the Phoenix Police Department and that women officers 'have to prove that they should be in the Department,'" the complaint states.
Milbourn, a former sergeant in the Army National Guard, says that she faced harsher criticism and was given different job duties and less favorable working conditions than her male counterparts.
The city's Equal Opportunity Department investigated and essentially concluded that Sergeant Chiappo just didn't like Milbourn very much.
The EOD's exact wording: "There is some evidence to support Officer Melbourne's claim that she was treated differently than other employees, but no evidence that the reason for any different treatment was based on her gender. The evidence shows that some male officers were also subjected to similar treatment and that other female officers were not treated like Officer Milbourn.
"It appears that Sergeant Chiappo had a lower tolerance for the actions of Officer Milbourn, but a higher tolerance for some of the other officers, male and female alike."
The report also notes that Chiappo denied saying that she was harder on women, "but reported making a similar remark with the intent of inspiring the female officers."
"The employees did not feel inspired, but rather felt that Sergeant Chiappo was telling them she was going to treat the female employees differently."
After filing her initial complaint, Milbourn returned to the Equal Opportunity Department to report that she'd faced retaliation as a result.
She told investigators that she and several male officers had violated an order given by Sergeant Chiappo, but she was the only one who faced any consequences.
After looking into her claims, the EOD concluded that "this difference in treatment gave creditability to Officer Melbourne's case of gender discrimination and casts a shadow upon the chain of command that enabled Sergeant Chiappo to continue her differential treatment of Officer Milbourn."
The EOD agreed that Chiappo had violated city policy and potentially also state and federal law by displaying "a retaliatory animus," and had created "a chilling effect" within the department.
Milbourn also filed a complaint with the federal Equal Employment Opportunity Commission, stating that she'd begun receiving poor monthly performance reviews ever since she'd reported the alleged gender discrimination. The EEOC also concluded that she'd experienced unlawful retaliation, but declined to file a suit of its own against the Phoenix Police Department.
According to a 2005 article in the Arizona Republic, Milbourn was a sergeant in the Arizona Army National Guard before joining the police force. In the wake of Hurricane Katrina, she was assigned to a platoon in Livingston, Louisiana, where she delivered supplies to flood victims and patrolled the streets of New Orleans at night to try and ward off potential looters.
A request for comment sent to her lawyer wasn't immediately returned on Friday morning.
Phoenix Police Department spokesman Jonathan Howard declined to comment on the lawsuit, but confirmed that both Milbourn and Chiappo are still employed within the department.
Chiappo didn't respond to a message sent to her email address at Glendale Community College, where she's currently an adjunct professor.
Her subject matter? Ethics.
You can download and read Milbourn's full complaint here: