Equitable tracing is based not on legal ownership but on the claimant's possession of an equitable interest. There are several advantages to equitable tracing; first, it can trace property now mixed with other property. In
Boscawen v Bajwa, Millett justified this by saying that "equity's power to charge a mixed fund with the repayment of trust moneys enables the claimant to follow the money, not because it is his, but because it is derived from a fund which is treated as if it were subject to a charge in his favour". A limitation is that where the property has been put into a bank account that no longer contains enough money to repay it, it cannot be traced. For equitable tracing to be valid, several things must be demonstrated. First, the equitable title must exist; it can be brought into existence by the courts, such as in
constructive trusts. Secondly, there must be some kind of
fiduciary relationship between the claimant and the defendant. If the property was transferred through breach of trust, it will not be necessary to establish such a relationship, because it already exists. In addition, property transferred through breach of trust may be traced to any third party (other than a purchaser in good faith), even if they did not previously have a fiduciary relationship with the claimant. Historically, the courts have been willing to be "generous in finding that the necessary fiduciary relationship existed", even going so far as to recognise relationships that did not exist at the time of the transfer.
Mixture of trust funds with trustee's funds Equitable tracing's greatest strength is its ability to trace into mixtures of money. Different rules apply in different situations; where the money has been mixed with the money of a trustee, where a trust fund has been mixed with another trust fund (or money belonging to an innocent volunteer), and where money has been transferred by mistake rather than malicious intent. Where the money has been mixed with the money of a trustee, the court's decision depends on the motive of the trustee. Because a trustee is expected to invest trust property and behave honestly, the courts may choose to find that the trustee transferred the money to further the goal of the trust. Since the trustee is assumed to behave honestly, any profits made may be assumed (by this "convenient fiction") to be made by the
trust money, and any losses from the trustee's personal funds. The alternate approach taken is the "beneficiary election" approach. This is that where trust funds are wrongly mixed with the trustee's personal funds, used for an investment, and the money is thus not recoverable, the beneficiaries are allowed to "elect" whether the investment is to be held as a security for the amounts owed to them, or whether to take the unauthorised investment as part of the trust fund. This is considered the exception, rather than the rule; in
Foskett v McKeown, Millett said that "The primary rule in regard to a mixed fund, therefore, is that gains and losses are borne by the contributors rateably. The beneficiary's right to elect instead to enforce a lien to obtain repayment is an exception to the primary rule, exercisable where the fund is deficient and the claim is made against the wrongdoer and those claiming through him".
Innocent parties and mistake Where funds are mixed with those of another trust, or mixed with the funds of an "innocent volunteer", certain general principles apply. As laid out in
Re Diplock, the principle applied is that the claimant's entitlement ranks
pari passu to that of the volunteer; each has an equal claim to their funds. Whether the fund decreases or increases in value, each party can claim a percentage equal to their contribution. The problem here comes if the mixed funds are used in unequal chunks to acquire other property. The long-standing rule is that established in
Clayton's Case; that the money deposited first is deemed to be spent on the first property purchased. The problem with this is that if the first property becomes less valuable than the second property purchased, the first claimant loses some of their money while the second claimant is able to claim their money in its entirety. The alternate approach is the previously mentioned
pari passu idea; whatever the total property is worth, the claimants get a share proportionate to their input, without assuming that the first claimant's money is tied to the first property purchased and the second claimant's money to the second property. In
Barlow Clowes International v Vaughan, the Court of Appeal applied a similar set of principles, holding that the size of the contribution and the amount of time the money was part of the mixed fund were the factors to be considered. Where payments have been made by mistake claimants may or may not be able to recoup their losses. The leading case is
Westdeutsche Landesbank Girozentrale v Islington LBC, where
Lord Browne-Wilkinson declared that a constructive trust would be created when the recipient of the funds became aware of the mistaken transfer. As such, ignorance of the mistake would not create a fiduciary relationship, therefore not a trust, and the property would be untraceable. ==Loss of the right to trace and defences==