Constructing Arguments for and against Substantive or Procedural Fusion

Constructing Arguments for and against Substantive or Procedural Fusion

Constructing Arguments for and against Substantive or Procedural Fusion. Constructing an argument is about stepping from one stage to another. Each stage must follow logically from the last. This does not mean – or necessarily mean – that it must follow as a matter of deductive logic, although it may do so.

Deduction refers to arguments of this nature; this is a very simple example.


  1. Socrates is a man (premise 1)
  2. All men are mortal (premise 2)
  3. Therefore Socrates is mortal (conclusion)

Deductive logic is mathematical in its exactness. There is only one correct conclusion. Legal argument need not be like this. There is room for reasonable people to disagree, but the argument must be convincing and based on sufficient evidence and “good enough” reasoning


As an argument this fails; it’s not convincing in any way. Why? Because the reason does not relate to the conclusion. Nuclear bombs are a particularly destructive way of waging war and nothing in our nationality means either that war is a good thing or that we need to have particularly destructive ways of waging it.


The UK must have nuclear bombs because the North Koreans definitely have them, the Iranians will soon have them, and those two regimes can only be trusted not to use them against us if we have the similar capability to completely wipe them out.


We may not necessarily believe that, but the argument is better. It is a deterrent argument – in the cold war it was called Mutually Assured Destruction or MAD ; it can be tested by asking for evidence that the North Koreans would be deterred (ie might they bomb us anyway) or for evidence that they wouldn’t bomb us unless we bombed them (which would point the opposite way.)



How does common law differ from equity?

Constructing Arguments for and against Substantive or Procedural Fusion

Procedural Fusion


  1. Equity is different therefore, the law is only procedurally fused


Is this an argument? No. It is at best assertion. It is an assertion because it provides no evidence for two things – firstly why is equity different from the common law? Secondly it assumes without proving it that equity ought to be different from the common law. Nonetheless, we can turn this into an argument.


  1. Historically the chancellor stepped in to do equity in circumstances where the rigidities of the common law did unintended injustices.
  2. The chancellor and his successors did this on a discretionary basis, concentrating on what was fair in the circumstances and were much more flexible and responsive to the facts than common law judges.
  3. This use of broad standards and discretion remains the case today. (eg equitable remedies – specific performance in contract are said to be discretionary, but damages are available as of right – there is no discretion at all)
  4. The methods that judges employ when using and developing equitable doctrines therefore differs from those they use in purely common law scenarios


So far this is purely a historical argument, and valid in those terms. We have not yet proven that only procedural fusion is appropriate. Another step is needed. For now, however, note that these steps build on each other. Step 4 cannot be true if step 3 is false. Step 3 provides the evidence for the statement in step 4. Step 3 may be false even if steps 1 and 2 which refer to the past history of equity are true. I might object that things are different today. I might say that I accept the history, but that equitable remedies are not discretionary today. I might say that if damages are inadequate I have a right to specific performance and provide evidence for that. I might then say step 3 is false therefore step 4 is false.


In other words each step of the argument needs to be supported. Either it must be true if the previous step is correct, or evidence must be provided. That evidence can and must be evaluated and counter-evidence put.


  1. Equity is different therefore we only have procedural fusion.


Well not quite. We may have proven that equity is different, but I might object that we should work towards changing that. You might support your argument by saying that it is so different that it would be impossible to change. Indeed you might go on to say that the methods adopted in common law are such that it needs correcting every so often and the law would be worse if it could not be. You might also object that statute would need changing – section 49 Senior Courts Act 1981 states that equity prevails over the law. If equity were not different (and statutorily entrenched as different) this would make no sense. However, I might reply that section 49 does not preclude substantive fusion – it merely says that if law & equity conflict equity prevails; if we substantively fused the two then ex hypothesi they would not conflict. That would simply mean that section 49 had no area to operate in.


“Worse” is a value judgment. Some things can be proven right or wrong. If step 3 is correct it is wrong to say that equity and the common law have the same approach to remedies. To say the law would be worse is unprovable, although it may be unconvincing. Many legal arguments are like this – arguments that the law would be better or worse if… That does not mean you do not have to provide reasons though. I would have to argue eg that the law would create specific injustices (and say what they are) if equity were not available to correct it.


The arguments current in the debate at present revolve around whether step 3 is really right, and therefore whether the two jurisdictions are methodologically so different that substantive fusion would be impossible. Henry Smith for example clearly believes it is different. It has a separate function, providing broader more discretionary standards to preclude opportunistic behaviour impossible to predict ex ante. Is he right?


Substantive Fusion

Constructing Arguments for and against Substantive or Procedural Fusion

  1. The law needs to be coherent therefore substantive fusion is necessary


Is this an argument? No. It is again merely assertion. It assumes that without substantive fusion the law is incoherent without providing any evidence for this. Let’s try again.


  1. I accept that historically equity was concerned with broad standards of fairness and unconscionability, but it no longer is.
  2. In any case the common law is also concerned with standards of fairness.


So prove it. If I put a gun to your head and make you give me your money the common law doctrine of duress let’s me recover it. If I am completely lovesick for a ghastly grasping harridan who milks me for all I’m worth and give her all my money the equitable doctrine of undue influence lets me recover it. In both cases we might say it’s fair to give me the money back. Both the common law and equity engage in the same type of moral reasoning. Maybe I can also provide evidence that I have a right to specific performance or that there really isn’t much in the way of discretion in equity


  1. So the reasoning judges employ in equity and common law isn’t that different after all.
  2. If that is right substantive fusion is possible.


But I haven’t proven that it is desirable. Nor have I proven that without it the law is incoherent. More steps are needed. Burrows provides those steps (AS Burrows ‘We do this at Common law but that in Equity’ (2002) 22 OJLS 1). But again each needs testing.


  1. Sometimes equity and the common law try to do the exact same thing in different ways. The rules for calculating the claimant’s loss when damages are claimed may be different from those when equitable compensation is claimed. This is incoherent because history cannot justify that sort of difference. If method A is good for calculating loss here; it must be good for the same task there.
  2. But sometimes equity and the common law are different – legal proprietary rights are as we saw different from equitable. They are treated differently, but they are different. Contract is treated differently from tort – so what? They’re different. Negligence is treated differently from defamation – but so what?


I find this convincing. Steps 5 and 6 provide evidence that there are or may be cases where things are done differently for no good reason. That is incoherent and substantive fusion, allowing us to unify the jurisdictions where necessary prevents that.


You need not find this convincing – what evidence might there be that the argument fails. Can you for example find evidence that step 3 fails? Is there an assumption that history does not matter much here, remembering that the doctrine of precedent is essentially one rooted in the past. If equity worked differently from the common law pre-Judicature Acts, does precedent necessarily mean it works differently now? If so, we cannot ignore our history, and perhaps we need to concede substantive fusion is impossible – except by statute.

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