Since 2010, Geoffrey has extensively developed his practice in international administrative law, representing various clients in written and oral proceedings before the internal justice systems of various Hague-based International Organisations including the Organisation for the Prohibition of Chemical Weapons and the European Patent Office and subsequently before the Administrative Tribunal of the International Labour Organisation.

Areas in which he specialises include:

- Sexual harassment and harassment
- Staff benefits, entitlements and immunities
- Abolition, reassignment and reclassification of posts
- Appraisals and references
- Disciplinary offences, including violations of obligations of confidentiality
- Termination of and non-renewal of contracts
- Non-selection
- Sick leave and health issues
- Budget of and authority over the staff representative bodies
- Rights and obligations of non-staff members including consultants and independent contractors