Yes. The Agreement quite clearly called for dispute resolution by a neutral party – at that point the British Consul-General of North Borneo – in the event of a dispute. That’s an arbitration clause.

Here’s the translation of the clause on Sabah’s own web site:

In case any dispute shall arise between His Highness the Sultan his heirs or successors and the said Gustavus Baron de Overbeck or his Company, it is hereby agreed that the matter shall be submitted to Her Britannic Majesty’s Consul-General for Borneo.

Some have argued that this can’t be a proper arbitration clause because the word “arbitration” doesn’t appear in the original. That would be difficult, since the single word “arbitration” didn’t exist in Jawi – the language of the contract – at that time.

Another argument might be that, because the British Consul-General no longer exists, there can be no arbitration under this clause. The Spanish court disagreed with this, which is exactly why it appointed Stampa in 2019.

Generally, in international law, the principle of favor arbitrandum militates in favor of construing a clause as a valid arbitration clause if it seems at all possible that it was.

There are questions at the margins that were the subject of the arbitration, and that Malaysia could have asked during the arbitration process but chose not to: was this a binding clause (i.e., did the Consul-General have the right to decide any dispute, or was he merely invited to give his opinion)? This was the reason Dr. Stampa set up the first phase of the arbitration, leading up to the Preliminary Award. If the Malaysian Government had taken it seriously, it might have made some valid contributions to its own benefit. But it chose not to at the time, avoided challenging the arbitration decision directly in court, and attacked Dr. Stampa instead.