A more thorough explanation:

Double value refers to a penalty that is twice the value of something. For example, if a tenant refuses to leave a property after the landlord has given written notice, the tenant may be required to pay double the yearly value of the property as a penalty. This penalty was established under the Landlord and Tenant Act (1730).

Example: If a property is worth $10,000 per year, the tenant who refuses to leave may be required to pay a penalty of $20,000.

Double voucher is a term used in a common-recovery suit. It refers to a voucher first by the fictitious tenant to the real tenant, and then by the real tenant to the common vouchee. This process is used to establish ownership of a property.

Example: In a common-recovery suit, the fictitious tenant may first voucher the real tenant, who then vouches the common vouchee. This establishes the ownership of the property and allows for the recovery of any damages or penalties.

Do ut des is a Latin term that means "I give that you may give." It refers to an innominate contract in Roman law where a party gives something in exchange for something that the other party is to give.

Example: A person may give money to a seller in exchange for a product. The seller then gives the product to the buyer, completing the do ut des contract.

A contract is an agreement between two or more parties that creates enforceable obligations. It can refer to the series of operative acts by the parties, the physical document that sets forth the agreement, or the legal relations resulting from the agreement.

Example: A person may sign a contract with a company to provide services in exchange for payment. The contract sets forth the obligations of both parties and creates a legally enforceable agreement.