A collision on December 15 last year between several horses during a race in Ashburton resulted in Megan Taylor falling off her horse.
The 23-year-old died of her injuries later that day.
Karen Parsons trained Red Orchid - the horse Taylor was riding - and told RNZ that four horses had fallen during the race.
In January, the Racing Integrity Board charged an apprentice jockey with riding carelessly.
The hearing is being held at Addington Raceway in Christchurch.