It has been decades since Tony Blair had his day in court.
That expertise could prove invaluable, particularly as there is only one precedent for a serving prime minister appearing in public before a judicial inquiry. John Major, the former Tory prime minister, gave evidence at the Scott Inquiry into the arms-to-Iraq scandal and was widely judged – against many expectations – to have acquitted himself well.
Mr Blair’s lawyers may not have wanted to remind him of other world leaders called to account for their actions in court.
In the second appearance this June, he put on a bravura performance blaming everybody, particularly the judges, for his woes. Blair will certainly shy away from some of Mr Berlusconi’s flamboyant phraseology, although he may want to indulge in a more modest spot of finger-pointing.
The prime minister’s good friend Bill Clinton, the former US president, could also offer Mr Blair some advice on courtroom etiquette. His testimony to a grand jury in the investigation into whether he perjured himself in the Monica Lewinsky case was delivered in private, although it was released to the media a month later.
Unlike Mr Blair who will have to tough it out in the public gaze of Court 73, Mr Clinton could relax and give his evidence by video-link from a White House office.
The former president packed his testimony with his usual charm and good humour but also a lawyerly skill for evading certain questions.
The prime minister’s fellow leaders all survived the experience at the time. But public opinion in each case hardened against them as the stigma of wrongdoing or sleaze hung over them.