The process that enables the original owner of property to identify his property or its substitute in the hands of a third party. Both the common law and equity have developed their own rules of tracing, the common-law rules being more limited. At common law, where the property being traced is money, the rules do not allow tracing to continue once the money has become part of a mixed fund (i.e. money mixed in a bank account with other money). Tracing in equity does permit the tracing of money through a mixed fund. However, tracing in equity is first dependant upon there being a fiduciary relationship (Westdeutsche Landesbank Girozentrale v Islington London Borough Council  AC 669 (HL). It is not, however, necessary for there to be a pre-existent fiduciary relationship: it may be that circumstances will have given rise to such a relationship. This requirement has been criticized on the basis that the courts are too willing to find a fiduciary relationship where one would not otherwise have been found to exist, particularly in a commercial context (Chase Manhattan Bank NA v Israeli-British Bank (London) Ltd  Ch 105), in order to facilitate the operation of tracing in equity. The different rules for tracing at common law and in equity have also been severely criticized (Foskett v McKeown  1 AC 102 (Lord Millett). Tracing should be distinguished from “following”, which simply involves tracking the same product from one place to another, because tracing enables the identification of new property by which the original property has been substituted (proceeds of sale, for example).