Why do judges disagree and publish their disagreements when cases get decided? After all, the Cabinet does not do so (openly at least), and our FTSE 100 companies do not generally do so, when their executives propose a merger or launch a new product.  Surely, judicial dissent is a recipe for diminishing the authority of the majority answer, and an invitation to self-indulgence on the part of the minority to re-fight lost and irrelevant battles.

Lord Kerr has given a very persuasive answer to both concerns in the Birkenhead lecture on 8 October 2012. But it is worth thinking about the alternative way of doing things, before making up your mind on whether the current way is the best way.

Lord Kerr gives an excellent example of why judges should not be restrained from speaking out, even if they are in a minority. Lord Rodger did so in O'Byrne, a consumer protection case; he disagreed with the judge at first instance, the Court of Appeal and the other members of the House of Lords about the meaning of a stray line in the judgment of the European Court of Justice (CJEU) at an earlier stage of the case. And Lord Rodger was ultimately vindicated when the case got to the CJEU again. He had articulated precisely what the CJEU had been trying to say in its previous judgment. And Lord Kerr gives other examples of this in different contexts – the ground-breaking dissent at a time when the time was not quite yet ripe for the dissent to hold sway. So, for example, Lord Atkin's famous dissent in favour of the liberty of the subject in the WWII detention case of Liversidge v Anderson:

"I view with apprehension the attitude of judges who on a mere question of construction, when face to face with claims involving the liberty of the subject, show themselves more executive-minded than the executive… In this country, amid the clash of arms, the laws are not silent. They may be changed, but they speak the same language in war as in peace. It has always been one of the pillars of freedom, one of the principles of liberty for which on recent authority we are now fighting, that the judges are no respecters of persons and stand between the subject and any attempted encroachments on his liberty by the executive, alert to see that any coercive action is justified in law. In this case I have listened to arguments which might have been addressed acceptably to the Court of King's Bench in the time of Charles I."

Or Lord Denning's brave cry for a general law of negligent mistatement in Candler v Crane Christmas, triumphantly endorsed by the House of Lords a decade later.

So if judges really believe that the majority has got it wrong, then they should say so, even if they are in a majority of one. Nine times out of ten, that will be that – the battle has already been lost, but on the odd occasion, the eloquent dissent will find its moment.

The principle that a judge can dissent is universal in the UK judicial system. Strasbourg, despite the number of judges who may sit in the ECtHR, does the same thing; many enjoy the dissents there precisely because they may be so damaging – because they do indeed severely undercut the authority of the majority. And even a supposedly concurring judgment may potentially do as much damage as a dissent: see Judge Bonello's trashing of existing Strasbourg case law in Al-Skeini:

"Up until now, the Court has, in matters concerning the extra-territorial jurisdiction of Contracting Parties, spawned a number of 'leading' judgments based on a need-to-decide basis, patchwork case-law at best. Inevitably, the doctrines established seem to go too far to some, and not far enough to others. As the Court has, in these cases, always tailored its tenets to sets of specific facts, it is hardly surprising that those tenets then seem to limp when applied to sets of different facts. Principles settled in one judgment may appear more or less justifiable in themselves, but they then betray an awkward fit when measured against principles established in another…

"The truth seems to be that Article 1 case-law has, before the present judgment, enshrined everything and the opposite of everything. In consequence, the judicial decision-making process in Strasbourg has, so far, squandered more energy in attempting to reconcile the barely reconcilable than in trying to erect intellectual constructs of more universal application. A considerable number of different approaches to extra-territorial jurisdiction have so far been experimented with by the Court on a case-by-case basis, some not completely exempt from internal contradiction.

"My guileless plea is to return to the drawing board. To stop fashioning doctrines which somehow seem to accommodate the facts, but rather, to appraise the facts against the immutable principles which underlie the fundamental functions of the Convention."

But the great exception to the rule in favour of dissent is of course the EU Court, and in case you are wavering on whether dissent is a good idea, read on.

The CJEU is drawn from judges from all the EU countries, and is the supreme adjudicator of EU law, which, as I pointed out in a recent post, is tentacular in its reach – with human rights issues arising endlessly. The CJEU only gives one judgment. But how does it do it, given that there may be up to thirteen judges sitting on one case? Surely the Brits can't agree with the French, and the Germans, and the Greeks and the Latvians, all the time. Well, I don't suppose they do, but their disagreements may become suppressed into the 'agreed' judgment. As we all know, there are many ways of deciding the same case in the same way – with wildly different reasoning leading to the same end. And drafting that into an agreed judgment must be a nightmare, even if you agree on the answer. The exercise must be to come up with the irreducible minimum which the court can say to give its answer, hence a text which everyone can agree on, even though that may come across as rather bland. Ultimately, if a judge does not agree in the result, he or she may vote against the judgment – but the reasons for this, and the nature of any division, will never surface if they are out-voted in the result.

It sounds terribly corporatist, but it is all to a purpose – and it is the way that civilian law countries go about things in their own judicial systems. The idea of a judgment is to answer a question or series of questions. It is to help parties to work out how the result in the next case should be arrived at – not to give them multiple PhD theses on the topic which send the lawyers into ecstasy but everyone else into puzzlement. And therein lies part of the danger of the UK and Strasbourg system. All judges can write their own opinions. This happens as much if not more with concurring judgments, as with dissenting ones. If there is a sharp difference between two concurring judges (say, one rubbishes the human rights claim but rates the legitimate expectation claim, and the others do vice versa) then this has to be articulated – even though the later courts may find it difficult to decide just what is the binding element of the decision – the precedent which later courts may have to follow – depending where they are in the system.

But if two or more judges are saying essentially the same thing in their different language, then why say it twice? Because it just encourages lawyers like me to argue that in fact they may be saying rather different things – so I claim that the majority is not as unanimous as it may seem. I readily understand the intellectual discipline which writing a judgment requires – making sure that you have indeed got to the right answer in your own way  – but what about spiking it when your judicial colleague has really arrived at the same conclusion? Or agreeing that the particular differences between the judges don't matter, and so that only one majority judgment is needed (even if it has bits of two judges' texts in it). I am sure this happens all the time in Parliament Square (see Lord Kerr's account of how drafts go backwards and forwards between the Justices in the Supreme Court there), and indeed the Royal Courts of Justice (between judges in the Court of Appeal), but more often and more copy left on the editing-room floor, please.

So, like most UK lawyers, I suppose, I support strongly the right to dissent, even though it comes at a cost – namely that of having to comb through more judgments than might appear necessary at first glance. At least you should know where all the judges stand once you have done it. And you don't end in the situation in O'Byrne where an unclear committee-drafted remark by the CJEU in round one means that the parties have to go to Luxembourg for a second time. More fundamentally, how could Lord Atkin (believing what he wrote in his dissent – see above) put his name to a judgment which said precisely the opposite?

David Hart QC is a barrister and contributor to the UK Human Rights Blog, which is written by members of 1 Crown Office Row.