Where something goes badly wrong at a hearing it is sometimes necessary for the advocate who was present to explain events as part of the appeal process. It has become customary in immigration proceedings for the advocate to have to write a witness statement and therefore, because he or she is by doing so giving evidence, to stand down from the case and hand over to a colleague. Upper Tribunal judges have seemed insistent that an advocate can barely breath a word of what might have happened at the previous hearing without spontaneously combusting.
As far as I am aware, this is unique to immigration law. I once had an issue like this myself and approached my joint heads of chambers, both very senior and well respected family law barristers, to check that I was indeed obliged to stand down from the case, which was what I had been led to believe by my experience in the immigration tribunal. I remember the discussion well: they simply did not understand what I was saying. “But you best know what happened and can best explain the issues, surely the appeal court will want you to retain conduct of the case?” one said. “You can’t just give up on your client like that, you are obliged to retain conduct if you possibly can,” said the other.
The difference in approach between immigration law and the rest of the legal world is perhaps explained by what sometimes feels like a lack of trust and respect between advocates and judges, by the distorting effect of how the Home Office chooses to be represented and by some of the other oddities of the immigration tribunal. For example, advocates for opposing parties would normally be able to agree on any deficiencies in the hearing process and any such agreement would be accepted by the appeal court. That is basically impossible where the Home Office is so impossible to communicate with and where there is no continuity of representation. Normally, the judges will have had some direct experience themselves as advocates or lawyers in the area of law in question, which is unusual in the immigration tribunal. Normally, there would be little chance of an unfair hearing or allegations of unfairness in the first place because both sides would be robustly represented and the judge would make a decision on the case there and then rather than going away to think about it and potentially come up with new ideas that were not articulated in the hearing.
A marriage between the two approaches is attempted in BW (witness statements by advocates) Afghanistan  UKUT 00568 (IAC), a determination from the President of the Immigration and Asylum Chamber, Mr Justice McCloskey:
Where an advocate makes a witness statement in the circumstances outlined above, a change of advocate may be necessary, since the roles of advocate and witness are distinct, separated by a bright luminous line. An advocate must never assume the role of witness.
The President makes clear, though, that it will be rare that this is necessary, and it will not be necessary where unfairness is apparent on the face of the determination in question. It is possible to discuss what happened at the hearing without giving evidence.
On the facts of the case, the alleged unfairness had arisen when the First-tier judge had declared his decision on a key issue before submissions had been heard on it. The advocate had prepared a statement to accompany grounds of appeal and stood down as advocate. The Home Office did not dispute the allegation and conceded there was error of law, a concession the Upper Tribunal considered was properly made. The case was remitted for re-hearing by a different judge.