[2][3] He was educated at Bishop Wordsworth's School in Salisbury, Wiltshire before studying Philosophy, Politics and Economics at St Edmund Hall, Oxford from 1971 to 1974.
[8] As a junior barrister he defended a number of terrorist suspects (both Provisional IRA and those from the Middle East), fraudsters and major drug dealers.
[10] Government officials, including both the Attorney General and Solicitor General defended the appointment as it had been made by an independent board consisting of First Civil Service Commissioner Usha Prashar; Hayden Phillips, the Permanent Secretary at the Department for Constitutional Affairs; David Omand, the Cabinet Office Permanent Secretary; and Robin Auld, a Lord Justice of Appeal.
[14] Macdonald's predecessor also dismissed the relevance of the drugs offence and a report in The Independent also found support for his appointment from within the legal system.
He was prominent in criticising government attempts to extend pre-charge detention to 42 days, arguing that due process protections should not be undermined and that the reform was unnecessary.
[17][18] In his last month in office he warned against excessive use of surveillance powers being introduced by the government, saying: "We should be careful to imagine the world we are creating before we build it.
[20][21] Macdonald retired as DPP on 31 October 2008, returning to private practice at Matrix Chambers and becoming a regular contributor to The Times, where he writes on law, security and politics.
"[26] On 28 May 2010, Downing Street announced that Macdonald would be made a Liberal Democrat life peer in the 2010 Dissolution Honours List,[27] which was gazetted on 15 June.
[29] On 13 July 2010, Theresa May, the Home Secretary, announced to Parliament that she had invited Macdonald to oversee a government review of counter terrorism and security powers, to ensure that legislative measures in place were proportionate and consistent with the rule of law.
[31] In January 2011, it was announced that Macdonald was to succeed the late Lord Bingham of Cornhill as the chair of Reprieve, the leading international anti-death penalty and prisoners' rights organisation.