Capacity to Litigate
The link is to a case which looked at an Adult's ability to litigate and when a "next friend" should be appointed.
Para 58 is quite clear:The authorities are unanimous in support of two broad propositions. First, that the mental capacity required by the law is capacity in relation to the transaction which is to be effected. Second, that what is required is the capacity to understand the nature of that transaction when it is explained.
Generally English Common Law is not that bad. After all much of the ECHR is based upon it. On the issue of capacity to litigate it is clear that this capacity relates to understanding not the litigation, but the issue about which the litigation is ensuing.
All we need to do, therefore, is to find some way in which English Common Law can be applied to courts in the Family Division and we will be away.