In Roman and civil law, it is a contract (fiduciary contract) in which one party is entrusted with specific fiduciary duties or responsibilities. An example is a principal-agent relationship: the agent acts on behalf of his/ her principal in a fiduciary capacity- that is, as a trustee.

In a specific context, it is a contract of sale (essentially a contract of sale) where a purchaser agrees to sell the object of sale back to the seller upon the fulfillment of certain conditions. The sale is carried out by mancipation / by mancipatio or cessio in jure (in Roman antiquity, a legal formality whereby title to property is acquired, whether by actual or by simulated purchase). This also includes cases where a contract is coupled with a condition that if a certain amount is paid by a specific day, the property shall be re-conveyed.

In Roman law, fiduciary contracts belong to a wider class of contracts known as real contracts (which includes in addition to fiduciary contracts: pledge, bailment, and deposit. All these contracts are entered into in good faith (bonae fidei).

This contract is also known as fiducia.