A producer can decide not to grade his grain, but he must accept the grading determined by the first buyer. However, if he wants to challenge the buyer's grading, he can always grade his own grain.
Graders are all trained by the Régie des marchés agricoles et alimentaires du Québec and are accountable for their decisions. If it were to happen repeatedly that a grader improperly graded the grain, he would have to take the course again, because otherwise he could lose his certification and perhaps even be prosecuted, if there is a belief that he was dishonest in establishing the grading. That's why it is extremely rare for grain to be improperly graded. It is graded two or three times, and in 97% of cases, the result is the same each time.