What is the test for arbitrariness?

38 In this case, the respondent was accused of acting negligently; negligence is equivalent to arbitrariness for the purposes of this complaint. This refers to the quality of its representation. Even if there is no intent to harm, a bargaining agent may not process an employee’s complaint superficially or carelessly. It must investigate the complaint, review the relevant facts, or seek whatever advice may be necessary. However, the employee is not entitled to the most thorough investigation possible (see Noël v. Société d’énergie de la Baie James, 2001 SCC 39 at para. 50).