205 / 522
At this point, if the new claims are withheld based on purely tacti-
cal reasons, the arbitral tribunal may take a restrictive attitude.
Especially if there are factors to be weighed against the belated intro-
duction of new claims, such as the parties submitting new evidence and
arguments respecting the new claims
5
, they are more likely to be
rejected by the arbitral tribunal. These issues may later cause due
process concerns, which would, in turn, cause obstacles in enforce-
ment proceedings.
If the new claims are not authorized by the arbitral tribunal, the
party who intends to introduce these claims, should initiate separate
arbitration proceedings.
Conclusion
The requirement of the arbitral tribunal’s authorization for new
claims under Article 23(4) is important, since it imposes on the parties
to make every effort to concrete their claims in the terms of reference,
in order to draw the lines of the arbitration proceedings. If the parties
wish to introduce new claims after the terms of reference are estab-
lished, whether these claims shall be authorized or not would be sub-
ject to Article 23(4) of the Rules. The arbitral tribunal has extensive
discretion on this matter, and would consider many factors, such as the
nature of such new claims, and the stage of the arbitration. The arbitral
tribunal may also consider other relevant circumstances, such as
whether the claims could have been introduced earlier in the proceed-
ings, and whether they impose an additional burden on the other party.
ARBITRATION LAW
189
5
Webster/Bühler
, p. 366.