Labour. The Society of United Professionals v. New Horizon System Solutions
In The Society of United Professionals v. New Horizon System Solutions (Ont CA, 2020) the Divisional Court stated the leading doctrine on interferance with a union's representation of employees in the bargaining unit [s.70 of the Ontario Labour Relations Act]:
 Section 70 of the Act provides:
No employer or employers’ organization and no person acting on behalf of an employer or an employers’ organization shall participate in or interfere with the formation, selection or administration of a trade union or the representation of employees by a trade union or contribute financial or other support to a trade union, but nothing in this section shall be deemed to deprive an employer of the employer’s freedom to express views so long as the employer does not use coercion, intimidation, threats, promises or undue influence. (emphasis added) Both parties had agreed at the hearing before the Board that the leading cases on the interpretation and application of s. 70 are Hotel & Restaurant Employee CAW Local 448 v. The Millcroft Inn Ltd., 2000 CanLII 12208 (Ont. L.R.B.) and Bernard v. Canada (Attorney General), 2014 SCC 13. In both these cases, the issue was whether s. 70 or a similar provision requires that a trade union be provided with contact information, such as home addresses and phone numbers, for the members of the bargaining unit it represents.
 In Millcroft, the Board set out the test for applying s. 70 (at para. 16):
A violation of section 70 of the Act does not require an anti-union animus. If the result of certain conduct is interference in the union’s capacity to represent its members, that can be sufficient to constitute a breach of the provision. The conduct may be lawful and bona fide; it may be free of any anti-union taint, yet if its effect is to harm the union’s capacity to represent its members, it may be a violation. It will be a violation if there is no business rationale for the interference.In Bernard, the Supreme Court of Canada quoted the Millcroft decision with approval. In each of these cases, it was held that access to the employee contact information was necessary for the union to carry out its representative obligations.