The exclusive negotiator is generally referred to as a „union“. Question: How can companies safeguard the right to collective bargaining? The history of the parties` behaviour towards each other in the past, reflecting the parties` expectations of negotiations in the future. Such practices, which are sanctioned by use and acceptance, are not expressly included in the collective agreement. To constitute a previous practice, the question must be: (1) clear to the parties; (2) consistent in its application over a certain period of time; and (3) tolerated by the parties. Arbitrators use past practice to interpret ambiguous language in the collective agreement. .