Joinder is the method by which a person (or persons) with whom common questions of law or fact arise can be joined to existing proceedings. The advantage of joinder is that the parties so joined become subject to orders of the court, including disclosure obligations as a result of their party status. If they give evidence, other parties will also have an automatic right to cross-examine them. In this way, joinder can assist the court in investigating and resolving issues.
In financial remedy proceedings, joinder is governed by FPR 2010 r9.26B. This rule was only inserted in 2012 – prior to that, courts had been forced to rely on the old Rules of the Supreme Court 1965, as in Goldstone v Goldstone  EWCA Civ 39.
The power to join a party may be exercised either on the court’s own initiative, on the application of an existing party, or of someone who wishes to become a party. Applications for joinder are made in accordance with the Part 18 procedure, per r9.26B s.1(5).
It is important to note that where property is in a respondent’s name but is held by a third party, the applicant is under an obligation to join that person as a party at an early stage, as detailed in TL v ML (Ancillary Relief: Claims against Assets of Extended Family)  1 FLR 1263. In that case, Nicholas Mostyn QC (as he was then) provided guidance for situations in which a dispute arises about the ownership of property in ancillary relief proceedings between a spouse and a third party. He regarded the following steps as essential:
i. The third party should be joined to the proceedings at the earliest opportunity;
ii. Directions should be given for the issue to be fully pleaded by points of claim and points of defence;
iii. Separate witness statements should be directed in relation to the dispute; and
iv. The dispute should be directed to be heard separately as a preliminary issue, before the FDR.
The test for FPR 2019 9.26B s.1 provides that ‘The court may direct that a person or body be added as a party to proceedings for a financial remedy if – (a) it is desirable to add the new party so that the court can resolve all the matters in dispute in the proceedings; or (b) there is an issue involving the new party and an existing party which is connected to the matters in dispute in the proceedings, and it is desirable to add the new party so that the court can resolve the issue.’
The key question that a court will consider when hearing an application for joinder is therefore whether the proposed joinder is ‘desirable’ in order for the court to resolve the issue in dispute. There are conflicting cases on how this has been applied in the High Court in relation to trustees.
In DR v GR  EWHC 1196, Mostyn J reviewed r9.26B as to the practice in relation to the joining of trustees in variation of settlement cases. He held that joinder is not an essential pre-condition for the validity of a variation of settlement order. He went on to outline:
i. The applicant for joinder must show either:
a) that there is an existing matter in dispute which requires for its resolution the joinder of the new party, o
b) that there is a matter in dispute between a party and the proposed new party which is connected to the main matters in dispute between the parties and that it is desirable to resolve all the issues together.
ii. Under the first limb it must be clearly shown that an existing matter in dispute between the parties cannot be effectually and validly resolved without the joinder of the proposed new party.
iii. Under the second limb it must be shown that there is a separate dispute between a party and the proposed new party and that it is desirable to hear the matters together. The question of whether it is desirable to hear the matters together extends to the commonality of evidence as well as the saving of costs.
In the more recent case of TM v AH  EWHC 572 (Fam), Moor J came to a rather different conclusion – namely, that in a variation of nuptial settlement case, the trustees would almost invariably need to be joined in order to make the result binding on them. Moor J addressed Mostyn J’s view that matters could be determined once the trustees had been served without the trustees needing to be parties, and commented: ‘I have to say that it is not my experience that the court regularly deals with such matters without joining the trustees. Indeed, my experience is to the contrary, namely that the trustees are joined when there is an application to vary the trusts of which they are the trustees.’ Moor J went on to consider the decision of Munby J (as he was then) in A v A and St George's Trustees  EWHC 99 (Fam), in which it was made clear that trustees had to be joined for orders to be binding upon them. Moor J also considered Article 6 of the European Convention on Human Rights, which concerns the right to a fair trial, and expressed his view that to make an order that would be binding on a person, without them having been a party in that litigation, may violate that right.
So, which judgment is to be preferred? The commentary to the Financial Remedies Practice 2019 notes that Moor J’s position in TM v AH does not appear to be consistent with the statutory scheme, which only provides for service on trustees, and not mandatory joinder. There is not, as of yet, any clear guidance as to which judgment to follow. However, there is a clear policy objective of enabling parties to be heard if their rights could be affected. And of course, in interpreting any rule of the FPR, the court must give effect to the overriding objective, which imposes an obligation for the court to deal with a case ‘justly… expeditiously, and fairly.’ Fairness may seem to dictate that a person should not be bound without having been a party – just as Moor J articulated in TM v AH.