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Jefferi is a Disputes lawyer specialising in arbitration and public international law.

Jefferi has experience supporting clients on a range of public international law issues, including in connection with investment treaty arbitration, business and human rights, and transboundary resources.

Jefferi has worked on both contentious and advisory investment treaty arbitration matters and has previously been involved in the implementation of treaty protection-related advice through investment restructuring. Jefferi has also worked on advice in relation to business and human rights issues, covering points of international human rights law and sector-specific human rights due diligence responsibilities.

Additionally, Jefferi regularly advises clients in commercial arbitration proceedings. Jefferi has experience working on cases under various institutional arbitration rules, including those of the LCIA, ICC, SIAC and JCAA.


Jefferi holds a law degree from St John's College, University of Cambridge, and an LLM (Public International Law) (Distinction) from the London School of Economics and Political Science.

Jefferi is a Malaysian national, and previously spent six months on secondment to the HSF Tokyo office.

Experience & expertise

Selected matters

  • a leading aircraft leasing company on an investment treaty claim against a State relating to the recovery of aircraft detained following Russia's invasion of Ukraine
  • a confidential client on public international law issues in relation to the development of a gas field that straddles an international boundary
  • an energy company in a dispute under the LCIA-MIAC Rules in relation to a power purchase agreement
  • a biotechnology company in an arbitration relating to one of the leading Covid-19 vaccines
  • a major Japanese pharmaceutical company in JCAA arbitration proceedings for claims of breach of representation and warranty under a share purchase agreement arising out of the sale of a pharmaceutical company