On March 5, 2009, Mr. Thomas sent to the parties through the PCA a letter updating them as to changes in his professional situation. He indicated to them that "[e]ffective 15 June 2008, [he] became a sole practitioner practicing through [his] personal law corporation." He further indicated:
My files are administered and maintained autonomously from BLG. My law corporation has separate computer, financial records, and telecommunications system. As a part of my consultancy agreement, I can assist BLG in a particular matter if both firms have cleared their conflicts checks. Neither firm has access to the other’s computer systems, internal communications and file openings, etc.
In the same letter of March 5, 2009, Mr. Thomas brought what he described as a "recent development" to the parties’ attention:
I have recently been advised by BLG that the Government of Mexico has decided to retain it to provide legal services to it for the period 1 March to 31 December 2009. The government sought agreement that I could (through BLG) advise on specific legal matters as they arose and I agreed to that request.
On June 15, 2009, counsel for the Claimant wrote a letter to Mr. Thomas inquiring about the following:
We would appreciate receiving confirmation from you as to whether you have already commenced the work contemplated in the retainer agreement mentioned in your letter. Could you also please confirm whether the retainer agreement contemplates the provision of legal research, advice or representation with respect to the interpretation or application of the provisions of NAFTA Chapter 11, or similar provisions in Mexico’s Bilateral Investment Treaties?
On June 22, 2009, Mr. Thomas replied to the Claimant’s letter of June 15. He stated:
Since BLG’s retainer entered into force, I have done a small amount of work for BLG on Mexico-related matters, consisting principally of reviewing its advice in respect of matters that fall within the rubric of international trade and investment law. I have not provided representation to Mexico in respect of the interpretation or application of the provisions of NAFTA Chapter 11 or similar provisions in Mexico’s Bilateral Investment Treaties. I estimate that my time spent in this regard amounts to less than 5% of my time spent on professional matters.
On July 20 and 21, 2009, the parties proposed different schedules for the filing of further submissions on the challenge to Mr. Thomas. On July 22, 2009, I wrote to the parties on this point, informing them that I had decided:
(1) to invite the Claimant to file any further observations that it may have on the challenge by July 27, 2009;
(2) to invite the Respondent to file any further observations that it may have by August 10, 2009;
(3) to invite Mr. Thomas to file any additional comments that he may have within ten days of his receipt of the Respondent’s submission;
(4) to invite the parties to file simultaneously any further comments that they may have within ten days of their receipt of Mr. Thomas’ comments; and
(5) to reserve the possibility of inviting further submissions if deemed necessary.
For the reasons discussed above, I have decided:
(1) the Claimant’s challenge to Mr. Thomas is timely;
(2) the Claimant’s challenge is rejected;
(3) Mr. Thomas is requested to inform me within seven (7) days of his choice between continuing to advise Mexico and serving as an arbitrator in this case;
(4) each party will bear its own costs in respect of this challenge.