On May 6th, Arbitrator Michel Picher dismissed a grievance in which a union claimed a right of access to a witness statement given by a member who had declined union representation in being interviewed.
The decision turns on the specific language of the collective agreement at issue, though each party made principled arguments – the union claiming a broad right of access based on its representational role and the employer arguing that the proposed disclosure of personal information was prohibited by PIPEDA.
Arbitrator Picher gave some credence to the employer’s argument by suggesting that consent to disclose personal information must be judged in the circumstances. He also rejected the union’s argument, stating that a union’s role as certified bargaining agent does not give it an “inherent right” to information about members that is generated in the course of their employment.
All About Information 
Just based on your sketch, sounds like a reasonable decision. I can understand the union being interested (and even having a legitimate interest) in that information, but the privacy rights of the individual probably ought to be trumps.
Chris MacDonald
http://BusinessEthicsBlog.com