Contract Law · Formation of Contract

Valid, Void, Voidable, Illegal and Unlawful Agreements

Classify agreements correctly and explain how each category affects enforceability, restitution and collateral transactions.

10 min readReviewed by Advocate Aditya Sharma
Sections 2(g) to 2(j)Sections 19, 23, 24 and 65

In one line

The correct label tells you whether an agreement can be enforced, avoided by one party, or treated as prohibited from the beginning.

After this note, you should be able to

  • Distinguish void, voidable, illegal and unlawful agreements.
  • Connect each classification to the correct statutory provision and legal effect.
  • Avoid the common mistake of treating every void agreement as illegal.

The five categories

Classify the transaction before discussing remedies. Each label answers a different enforceability question.

Valid contract
The agreement satisfies Section 10 and is enforceable by law.
Void agreement
Under Section 2(g), it is not enforceable by law. It may be void from the beginning without necessarily involving prohibited conduct.
Voidable contract
Under Section 2(i), it is enforceable at the option of one or more parties, but not at the option of the other. Defective consent commonly creates this result.
Void contract
Under Section 2(j), a contract becomes void when it ceases to be enforceable. It may have been valid when formed.
Illegal or unlawful agreement
Its consideration or object is prohibited or falls within Section 23. It is void and may also affect connected transactions.

Void is wider than illegal

All illegal agreements are void, but all void agreements are not illegal.

An agreement may be void because the law declines to enforce it, such as an agreement that is uncertain. That does not automatically make the conduct forbidden. An illegal agreement involves a prohibited or unlawful object or consideration.

This distinction matters for collateral transactions. A collateral arrangement connected to a merely void agreement may survive, while a transaction inseparably connected with illegality may also be tainted.

How a voidable contract operates

A voidable contract remains effective until the protected party chooses to avoid it.

Who has the option
The option belongs to the party whose consent or legal interest was impaired.
Affirm or rescind
That party may affirm the transaction or seek rescission, subject to the governing rules.
Restoration
Rescission may require benefits received under the transaction to be restored where the Act so provides.

Restitution under Section 65

When an agreement is discovered to be void, or a contract later becomes void, a person who received an advantage may have to restore it or compensate for it.

Do not apply Section 65 mechanically to every void transaction. First identify why the transaction is void, whether the parties knew of the defect, and whether another specific rule governs restoration.

Work through the facts

Illustration

Facts

A obtains B's consent to a sale through misrepresentation. B later learns the truth but has not yet affirmed the transaction.

Likely result

The contract is generally voidable at B's option, not automatically void. B may choose whether to avoid or affirm it, subject to the facts and Section 19.

What to learn

Voidable means one party has an election. Do not write that the transaction never existed merely because consent was defective.

Cases with a purpose

Landmark judgments

Learn the rule and where to use it. A case name without its legal function adds very little to an answer.

Mohori Bibee v. Dharmodas Ghose

Core case

(1903) 30 IA 114

Principle: An agreement made by a minor was held void because contractual competence under Section 11 is essential.

Use in an answer: Use it to show a void agreement arising from lack of capacity, while saving detailed minor law for the capacity module.

Balfour v. Balfour

Core case

(1919) 2 KB 571

Principle: A domestic promise may remain unenforceable because the circumstances do not show an intended legal obligation.

Use in an answer: Use it to explain why not every agreement is a valid contract.

For a 10-mark answer

Answer structure

  1. Define the relevant categories using Sections 2(g), 2(i) and 2(j).
  2. State the Section 10 validity rule and Section 23 where illegality is alleged.
  3. Explain the legal effect, including who may enforce or avoid the transaction.
  4. Discuss collateral transactions or restitution only if the facts raise them.
  5. Apply a precise label and conclude clearly.

Common mistakes

  • Writing that void and illegal mean the same thing.
  • Treating a voidable contract as automatically void from the beginning.
  • Confusing a void agreement with a contract that later becomes void.
  • Discussing Section 65 without first explaining why the agreement is void.

Before you close the tab

Quick revision

  • Valid means enforceable.
  • Void agreement means not enforceable from the legal standpoint described by Section 2(g).
  • Voidable means enforceable at one party's option.
  • A void contract was enforceable but later ceases to be so.
  • Illegal agreements are void, but the category of void agreements is wider.

Test yourself

  1. What is the difference between a void agreement and a void contract?
  2. Who can avoid a voidable contract?
  3. Why are all void agreements not illegal?

Short answers

Frequently asked questions

Is a void agreement always illegal?

No. Some agreements are void because they are unenforceable, without the underlying act being prohibited. Illegality is a narrower and more serious category.

Does a voidable contract remain effective?

Yes, until the party entitled to avoid it validly rescinds it or the law otherwise brings it to an end.

Primary sources

This is an educational study note. Always read the bare provision and the full judgment before relying on a proposition in research or practice.