Following a collision between two Canadian National Railway trains in Quebec, an inspector from the provincial Commission de la santé et de la sécurité du travail initiated an investigation under the provincial Act respecting occupational health and safety.
The railway company challenged the investigation, arguing the provincial statute could not constitutionally apply to a federal undertaking.
The Supreme Court of Canada held that the provincial occupational health and safety legislation, because of its preventive nature, directly regulates the working conditions and management of the undertaking.
Consequently, the investigative powers under the Act are wholly inapplicable to an interprovincial railway undertaking.