Accessory liability concerns the remedies available against parties who, although not the fiduciary, are connected in some way to a breach of fiduciary duty — whether by receiving property, participating in the breach itself, or both. The general rule is as follows: third parties who knowingly participate in the default of a fiduciary may themselves be accountable in equity to the principal (Barnes v Addy). The doctrine of accessory liability provides a way for these other defendants to be liable for their role in breaches of fiduciary duties owed by other, in some way related, parties.