Walker was disqualified from the 2019 Pan American Games after she tested positives for metabolites of cocaine, believing that this came from drinking coca tea in Lima in Peru.

Her disqualification led to Canada's showjumping team being dropped for Tokyo 2020.

The sample was taken on the day of the team showjumping final at the Pan American Games in Lima, where the Canadian team, also including Erynn Ballard, Lisa Carlsen and Mario Deslauriers, finished fourth.

Canada secured a Tokyo 2020 quota place due to their finishing position, with berths awarded to the top-three teams who had yet to qualify for the Olympics.

Without Walker's scores at the Pan American Games, Canada slipped out of the final Olympic qualification place in team jumping which went to Argentina instead.

CAS heard the second parts of appeals via video link, with no timetable given for judges to deliver a verdict.

Walker has denied knowingly using cocaine.

Coca leaves and coca tea are not illegal in Peru and other countries in South America.

Her provisional suspension also dropped Walker down to 426th in the world rankings, while the International Equestrian Federation allowed her to return to competition in September.

Canada are one of the most prominent jumping nations, having won silver at Beijing 2008.

At Rio 2016, Canada finished fourth in the discipline.