Explanation: In common law (the legal system in which most rules come from case law or precedents, such as UK, US, Australia, etc), the contract is legally binding if it has the following requirements:
- Offer
- Acceptance
- Certainty & Intention to Create Legal Relations
- Consideration & Promissory Estoppel
- Legal capacity
According to these rules, 'Blanket order', 'One-off purchase', and 'Hire purchase agreement' are contractually binding. One of the reason is that they have consideration.
However, there is a type of legal instruments that does not need consideration to be legally binding. They are called 'Deeds'. A deed (anciently "an evidence") is any legal instrument in writing which passes, affirms or confirms an interest, right, or property and that is signed, attested, delivered, and in some jurisdictions, sealed. It is commonly associated with transferring (conveyancing) title to property. At common law, to be valid and enforceable, a deed must meet several requirements:
- It must state on its face that it is a deed, using wording like "This Deed..." or "executed as a deed".
- It must indicate that the instrument itself conveys some privilege or thing to someone.
- The grantor must have the legal ability to grant the thing or privilege, and the grantee must have the legal capacity to receive it.
- It must be executed by the grantor in presence of the prescribed number of witnesses, known as instrumentary witnesses (this is known as being in solemn form).
- In some jurisdictions, a seal must be affixed to it. Originally, affixing seals made persons parties to the deed and signatures optional, but seals are now outdated in most jurisdictions, so the signatures of the grantor and witnesses are primary.
- It must be delivered to (delivery) and, in some jurisdictions, accepted by the grantee (acceptance).