Past Practices Limit Parties’ Choices

History, frequency, maturity of relationship all figure in estoppel
By Gordon Sova
||Last Updated: 10/04/2007

The term past practice refers to a long-standing and consistent procedure or interpretation on the part of either an employer or a union that has resulted in the other party relying on that procedure or understanding in their dealings. Legally, it creates an estoppel: when a party has declared through its actions (or inactions) that it intends to interpret its rights in a certain way, and others have relied on these representations, it cannot then revert to a stricter interpretation of what these rights are.

What is the source of the right being contested?

Past practice comes into play in three different situations when dealing with a collective agreement. In some cases, a practice has been common and accepted despite the fact that it is contrary to the contract. In other cases, a practice of long standing concerns a subject on which the agreement is silent. Finally, arbitrators will use past practice to discover the meaning that has been given to agreement language that is ambiguous.