It is tempting in the time available to give a simple and short answer to the question. When investment treaties are drafted in exactly the same way they should be interpreted in the same way, when they are drafted in different terms they should be interpreted differently. But perhaps some further elaboration is in order.
Two points of principle confront us in the field of investment arbitration when it comes to what Emmanuel Gaillard has called the problem of precedent. The first is that the investment treaties which provide the source of jurisdiction and in most cases also the basis of claim, are, in principle, bilateral treaties concluded between different States at different times with, one supposes, the intention of those States as the primary factor to be taken into account. As is well known, there are over two thousand of these bilateral treaties.
It follows from that fact alone that the decisions reached by the tribunals sitting under these treaties, however we analyze them (whether as real international tribunals, or as derivative international tribunals, or as hybrids), are only binding on the parties and only in respect of the particular case.