Originally from Achnacarry in Lochaber, Donald was educated at the University of Oxford. He then worked at the Center for Strategic and International Studies in Washington DC – a think-tank specialising in international relations.
Returning to the UK to study law, he qualified as an Advocate at the Scottish Bar in 2005. He practised across Scotland focussing on public, agricultural and crofting law, appearing in the Court of Justice of the European Union, the Supreme Court, the Court of Session (Inner and Outer Houses) and the Scottish Land Court.
He was appointed a Standing Junior Counsel to the Scottish Government 2009-2016.
He was elected a Member of the Scottish Parliament for Highlands and Islands Region at the Scottish Parliamentary elections in May 2016 and currently acts as the Shadow Cabinet Secretary for Finance.
In Parliament, he is the Co-Convenor of the Cross Party Group on Health Inequalities and Vice Convenor of the Cross Party Group on Gàidhlig. He also sits on the Cross Party Group on Crofting, the Cross Party Group on Fishing, the Cross Party Group on Cooperatives and the Cross Party Group on MS, among others.