Since the Copenhagen Accord was not adopted by all Parties how legitimate was the Heads of State statement in Copenhagen?

It is difficult to see how it is not legitimate: a handful of parties agreed on the way forward (in the form of the HoS statement) and (as I understand it) they will present it to the COP for adoption. It is then up to the individual states to agree to it. If they don’t, the process starts again.

However, it is potentially arguable that the mandate of the AWGLCA from Bali was that the COP adopt a decision based on the work of the AWGLCA. Arguably then, the draft COP decisions that accompany the draft HoS statement must go through the AWGLCA but not necessarily the HoS Statement. The HoS can agree whatever they like. And ultimately, if the parties agree that the draft decision should be the ‘outcome’ of the AWGLCA, they are free to do so.

In short, it is difficult to argue against the HoS Statement, but potentially easier to do so against the draft decisions. Compromise is perhaps to adopt a HoS statement and ask the drafting groups to continue their work under the AWGLCA mandate.