Your question is too vague to answer. You might consider providing here the basis for why you think you can object/prevent their testimony. By "adequate preparation not accepted," if you mean the other party wouldn't allow you to depose them or didn't disclose they would testify, those could be valid reasons to move to preclude their testimony.
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There probably would not be any valid objection based upon merit. Although failure to disclose the identity of witnesses might be a basis to exclude such witness testimony, it is unlikely in an arbitration.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.
If disclosure was made within the rules, there really isnt a basis to exclude. if you were allowed discovery earlier in the case, and asked for discovery info that would have called for them to id these witnesses, and they didnt, you may be able to exclude. Arbitrator generally has broad discretion.
Now you know why consumer attys hate mandatory arbitration in employment and consumer contracts.