What is the test for vulnerability in the context of inequality in power?

Viewed in this light, the key question must be whether there was a degree of vulnerability that had the potential of materially affecting the ability, through rational autonomous decision-making, to protect one’s own interests. If so, a duty will be cast on the other party not to act or to refrain from acting in such a way that the resulting transaction is reached in a manner that involves the victim being unfairly taken advantage of. As expressed by Coutu J. in Floyd v. Couture et al at paragraph 146, “what is meant by inequality in power is where one party is at a serious disadvantage, so serious that they can be taken advantage of or exploited.”