IT HAS been quite a week for Aidan O’Neill QC. The advocate, who has been a QC in Scotland since 1999, took silk south of the Border on Monday, when he was the only member of the Faculty of Advocates among the 113 barristers to receive the honour in London’s Westminster Hall.

Although the process of applying for silk is notoriously onerous, Mr O’Neill said it was important for him to have senior status across the British Isles because “from the point of view of our legal systems Scotland and England are foreign countries to one another”.

“This is one of the conditions negotiated in the 1707 Acts of Union, which preserved Scots law and English law as distinct legal systems,” he said.

“When I started practising regularly before the courts in England and Wales, about five years ago or so, I became a junior counsel again.

“This felt a bit anomalous as I was regularly doing much the same kind of work - in public law, employment law, EU law and human rights - in England as I had been doing, and continued to do, in Scotland. So once I had become sufficiently well known to the judges in England and Wales through my court appearances there I thought I should try and regularise the position and formally apply for silk in England too.”

As a member of both Ampersand Advocates in Edinburgh and Matrix Chambers in London, Mr O’Neill is no stranger to the courts on either side of the Border. Recent Scottish cases have seen him appear in both houses of the Court of Session in a challenge to the law on assisted suicide, argue for St Margaret’s Children and Family Care Society in a Scottish Charity Appeal Panel case to do with discriminating against adoptive parents on religious grounds, and represent the Scottish Football Association in a case to do with Newcastle United owner Mike Ashleigh’s purchase of shares in Rangers Football Club.

In England, Mr O’Neill has handled numerous cases in tribunals and the Court of Appeal and is also a regular in the Supreme Court, the final port of call for claims originating in all jurisdictions in the UK.

Noting that the main difference between the English and Scottish courts is that in the former “there is now much more reliance on written notes of argument”, Mr O’Neill said he enjoys the challenge that brings in terms of “both sides having their time for oral submissions equally limited”.

This is not the case in the Supreme Court, where advocates must argue their case for extended periods before a panel of the country’s most senior judges, something Mr O’Neil said is “great fun”.

“I very much enjoy appearing in the Supreme Court,” he said. “It is the ultimate test of your advocacy skills to be up on your feet to speak – usually for two hours or more – before a bench of five or seven - or sometimes even 11 - of the brightest legal minds in the country, all of whom are fully engaged in the case and are testing the argument from all sides.

“The Supreme Court justices never speak with one united view from the bench, so you have to be alive to the fact that in asking you a question they may really be testing the position which they think another justice on the bench is tending toward. It calls on you to use to the full all the skills you ever need for this job in terms of persuasiveness, rhetoric, intellectual rigour, active listening and engagement, and being quick on your feet.”

In the Supreme Court Mr O’Neill recently mounted a successful challenge to the Scottish Government’s controversial named person service and he has been engaged to represent the Scotch Whisky Association in its challenge to the minimum pricing of alcohol.

While some of the cases he has been involved in raise controversial issues, Mr O’Neill stressed that, like all advocates, he never presents his own personal views but rather “argues the client’s case to the best of my abilities”.

“The whole justice system works on the basis that the best possible arguments are presented on both sides of a point so that the judges are able to reach the right decision on what the law requires,” he said.

To be successful in such an environment, Mr O’Neill said the top priority for all advocates should be to know the judges they are presenting to.

“If you did not adapt your advocacy style for the particular court and the judges you are before, you would not be doing the job properly,” he added.