[5] During his career he appeared for the Crown in the 2004 Glasgow Ice Cream Wars appeals, prosecuted the significant HM Advocate v Transco case in 2005, the first ever prosecution of a public limited company for culpable homicide in the country, and oversaw prosecution of the infamous 2007 World's End murder trial, which collapsed due to insufficient evidence and resulted in a public dispute between the Lord Advocate of the time, Elish Angiolini, and the Lord Justice General, Lord Hamilton.

The Lord Advocate at the time, Elish Angiolini, made a statement to the Scottish Parliament, saying she was "disappointed" at the decision.

Beckett, who had been junior defence counsel for Abdelbaset al-Megrahi in the Lockerbie trial, was subsequently appointed a floating sheriff.

[2] His appointment was approved by the Scottish Parliament without the need for a vote[14] and he was sworn in as Solicitor General at a ceremony at the Court of Session on 30 May 2007.

[16] Whilst Solicitor General, he formed the new Serious and Organised Crime Division within the Crown Office,[17] as well as leading the successful prosecution of Peter Tobin in 2007 for the 1991 murder of fifteen-year-old Vicky Hamilton.

[18] Mulholland was appointed Lord Advocate, the senior Law Officer in Scotland, following the 2011 Scottish Parliament election.

[5] The Judicial Office for Scotland announced that "Judge Mulholland will not hear any criminal case in which, by reason of his previous role as Lord Advocate and head of the prosecution service, he would require to recuse himself; nor any civil case involving the Scottish government which, given his former role as the Scottish government's principal legal adviser, he would again need to recuse himself.

[5] In 2021 Mulholland's successor as Lord Advocate apologised to Paul Clark and David Whitehouse for the decision to prosecute them in 2015[24] over the takeover of Rangers football club.

The former Labour MP Sir Brian Donohoe subsequently called on Mulholland to step down as a Senator of the College of Justice, saying his reputation had been badly damaged by the scandal.