Nattrass, one of Canada's most decorated athletes, earned her spot on the squad in a shootoff with longtime teammate Cynthia Meyer.
The trouble stemmed from the Pan Am trials in Tucson, Ariz. Nattrass was permitted to shoot 30 minutes late after her gun and car keys were inadvertently locked inside her rental car. Officials didn't deduct the standard three points for a late competitor, ruling Nattrass wasn't at fault.
Nattrass and Meyer tied, which led to a shoot-off that Nattrass won.
Meyer's request was thrown out by an arbitrator at a Sport Dispute Resolution Centre of Canada (SDRCC) hearing, Nattrass's lawyer said in a statement released Wednesday.
"We are ecstatic," Mark McMackin said in the statement. "This hearing was the fourth appeal on this matter — all of which were denied — and we feel this was a vexatious proceeding and a considerable waste of resources having included more than six lawyers and various staff from the Shooting Federation and the Sport Dispute Resolution Centre of Canada in Montreal from Saturday night to Monday, June 15."
The 64-year-old Nattrass is a six-time Olympian and a seven-time world champion. The Edmonton native was Canada's flag-bearer for both the 2007 Pan American Games in Rio, where she won gold, and the 2014 Commonwealth Games.
The case is the second in the span of a week where the selection of a Pan Am Games team has been questioned.
Archery Canada recently reached an agreement in the case of Toronto archer Kateri Vrakking, who alleged ageism was the reason for her exclusion from the Pan Am Games recurve team.
Despite finishing third in the Pan Am trials, the 42-year-old Vrakking was not originally included on the team, while Shannon Davidson, 19, the fifth-place finisher, was chosen to round out the three-member slate.
Archery Canada argued they chose the fifth-place finisher for the development of the sport. Vrakking won her appeal, and replaced Davidson on the team.