First of all, I would try contacting the union rep again (but in writing, say email), and get him to put his words in writing. Additional, I would also ask for clarification on what your options are should you want to proceed further. As your union representation, even though his explanation might be unsatisfactory to you, he is still obligated to provide you with the information you need to proceed further.
If you are still looking to escalate the issue, I think the next step beyond your union rep / shop steward is the union chair at your workplace. You can bring the issue directly to his attention, mentioning that you have already discussed the matter with your union rep. You might also want to get him to put something in writing -- again, I think email might be easier to solicit than something written on paper.
After that, if the informal resolutions aren't working, I think the next step is filing a formal complain. If an official ruling comes back and you are still unsatisfied, I think you can still file for grievance on the ruling and have a tribunal look at the issue. But beyond the filing of a formal complain, I think the specific rules and procedures would depend on the CBA or the union.
One unfortunate reality is, when your union rep doesn't agree with your view, there is a good chance that it'll turn into a long and drawn out ordeal. Coworkers related or unrelated to the incident might also start taking sides (although the smart ones will stand clear of the issue), and your relationship with the coworker in question will very likely deteriorate regardless of how the issue plays out. So you have to consider whether escalation is worth your trouble and the consequences.
Good luck with your decision la.
-Lik |