CMS’s co-head of international arbitration Mariel Dimsey has been named as the new secretary-general of Hong Kong’s International Arbitration Centre (HKIAC), replacing Sarah Grimmer who is due to leave in August.

Dimsey first arrived in Hong Kong with Hogan Lovells in 2016 before moving to CMS in 2018 and making partner a year later.

David Rivkin, Debevoise & Plimpton partner and HKIAC co-chair, said: “We are excited to welcome Mariel as the next secretary-general and look forward to her leadership.”

Grimmer’s deputy Joe Liu will also depart. He is set to be replaced by HKIAC managing counsel Eric Ng, who joined in 2019 following a successful first career in IT.

Ng, writing on LinkedIn, said: “One could not have asked for a better mentor than Sarah, and I very much look forward to building that relationship anew with Mariel Dimsey. Joe has set the high-water mark for the role that I now inherit, and I can only hope to meet that bar in the coming few years.”

Grimmer, who leaves after six years in post, will take up a position as an independent arbitrator at Twenty Essex in Singapore, while Liu is setting up his own arbitrator-only boutique practice.

Prior to joining HKIAC, Grimmer spent a decade at the Permanent Court of Arbitration and time at Paris’s ICC Court of Arbitration. Her tenure saw HKIAC rise in the rankings as the third most-preferred arbitral institution in 2021’s QMU/White & Case international arbitration survey, behind joint rivals London and Singapore. She also steered revisions to HKIAC’s arbitration rules.

Most pertinently, she enabled a pivot to virtual hearing services during the pandemic, with the Special Administrative Region (SAR) having imposed stringent travel and public health restrictions to combat Covid-19, many of which are still in place. 

HKIAC has nonetheless remained active internationally, albeit virtually, while in-person and hybrid hearings have also resumed with safeguards. Other Grimmer innovations include an award-winning digest of procedural decisions and significantly improved case management facilities.

The latter part of her tenure saw Beijing’s imposition of a controversial national security law in 2021, which subsequently saw two serving UK senior judges resign from the SAR’s Court of Final Appeal this year, citing rule of law concerns. Essex Court Chambers, famous for its arbitration work, was also sanctioned by China in 2021, disabling their ability to act in China, including HKIAC.

Notwithstanding, HKIAC’s caseloads have remained high, with record numbers of arbitrations in three out of the last six years, although cases fell in 2021.

Former Hong Kong justice secretary, Temple Chambers’ Rimsky Yuen SC and co-chair of HKIAC, said: “Sarah has been instrumental to HKIAC’s success over the past six years and we are all sad to see her leave.”

Duncan Matthews QC, head of Twenty Essex, said: “We are thrilled that Sarah has chosen to join Twenty Essex for the next stage of her career. Given her background, particularly with the HKIAC, she will be perfectly placed to enrich the expertise within our Singapore hub”, as well as globally.

Grimmer said it has been a pleasure to head HKIAC over the past six years. “I have had the good fortune of working with a very talented team, and the wonderful Hong Kong legal community,” including HKIAC councillors and staff, she said.

Liu, meanwhile, exits after eight years to set up his own arbitrator-only practice, JLIU Dispute Resolution. Liu served in progressively senior roles, including five months as acting secretary-general.

Liu, who did not seek promotion, formed an outstanding double act with Grimmer, including developing HKIAC’s practice processing applications for interim measures in the PRC courts, an award-winning tribunal secretary service, and successive 2013 and 2018 reforms to HKIAC’s arbitration rules.

Liu said: “I deeply value my time at HKIAC and feel privileged to be part of the institution’s path to success and excellence. Looking ahead, I’m excited about my new role and look forward to working as an independent, efficient and reliable arbitrator with my institutional knowledge, private practice experience and language skills.”