Justine is Global Chairperson of the firm and is a senior partner in the private client and tax team. She is also head of the Swiss Practice and leads the firm's Community, Planet and Impact initiatives.

Justine joined Withers in 1999, becoming partner in 2004. She founded Withers' Swiss Practice in Geneva in 2005 and has led it since that date. She co-headed the firm's Global Private Client and Tax team from 2016-19, when she was voted into the position of Chairperson. She has a very successful practice as a leading tax, trusts and estates adviser, working with international families on their succession planning and the structuring of their personal assets and business interests.