Having mandatory arbitration be a part of an employment contract seems like it is something that should be disallowed as part of employee protections. Or perhaps disallowing the choice of arbitrator by the employer would be sufficient.
I don't care (I don't think) if two companies agree to mandatory arbitration as part of their business dealings, in part because it seems more like a meeting of equals. But for vastly unequal negotiations (renters would also be a likely culprit) it seems like a 'works in theory, but not in practice'.
I know that in Canada, mandatory arbitration for consumers was disallowed recently in BC. Note that I'm not a lawyer or in the know, this is just a google search result: http://www.duhaimelaw.com/2011/03/18/supreme-court-of-canada...