Illusory Promises in Contracts: How Australian Businesses Can Avoid Them

When you sign a contract, you expect both sides to be bound to do something clear and concrete.

But sometimes a “promise” in a contract isn’t really a promise at all. If one party can perform only if they feel like it, or can change their mind with no real consequence, the obligation may be “illusory” - and that can jeopardise the whole deal.

In this guide, we break down what an illusory promise is under Australian contract law, why it’s a problem for businesses, and practical drafting techniques to avoid it. We’ll also walk through common examples and what to do if a clause is at risk.

What Is An Illusory Promise In Australian Contract Law?

An illusory promise is a statement that looks like a promise, but on closer analysis doesn’t actually commit the promisor to anything enforceable.

For a contract to be binding, you need offer and acceptance, certainty, and consideration (something of value being exchanged). If one party’s “promise” is so discretionary or uncertain that they can choose not to perform without consequence, there may be no consideration - and therefore no enforceable contract obligation on that point.

Courts typically ask: is there a real commitment, or can the promisor decide, for any reason or no reason, to do nothing? If it’s the latter, that clause (or the consideration supporting the contract) may fail for illusoriness.

Illusory promises are related to other formation and validity issues such as uncertainty, vagueness and agreements to agree. If key terms haven’t been properly nailed down, you also risk having an invalid contract or a clause that can’t be enforced as written.

Why Illusory Promises Make Contracts Risky For Businesses

An illusory promise can undermine the bargain you thought you had, increasing your legal and commercial risk. Common consequences include:

• Unenforceable obligations: If your counterparty isn’t actually bound to supply, pay or perform, you’re left exposed.
• Loss of consideration: If your promise is “I’ll buy if I feel like it,” there may be no consideration for the other party’s promise.
• Disputes and uncertainty: Vague or discretionary clauses can trigger costly negotiations or litigation.
• Regulatory exposure: Where dealing with standard form contracts, overreaching discretion clauses may draw scrutiny under Unfair Contract Terms (UCT) rules.

The good news is that careful drafting usually fixes the problem. Small tweaks - like adding objective criteria, minimum commitments, or a genuine option fee - can convert an illusory clause into a clear, enforceable obligation.

Common Clauses That Risk Being Illusory

Many illusory promises arise from everyday contract wording. Watch out for these patterns.

“Sole Discretion” With No Limits

Clauses that give one party the right to decide “in its absolute discretion” can be legitimate. The issue is when discretion is unlimited and covers the heart of the bargain (for example, pricing, quantity or whether to perform at all).

Example: “Supplier will deliver products as it determines, in its sole discretion.” If Supplier can choose to deliver nothing, that commitment is arguably illusory.

How to fix: Keep discretion for genuine judgment calls, but add guardrails - minimum quantities, service levels, objective criteria and reasonableness duties.

Agreements To Agree Later

“We’ll agree the price and delivery dates later” often indicates uncertainty rather than a contract. If the “agreement to agree” covers essential terms, the clause may fail - and with it, the consideration supporting the deal.

How to fix: Use objective mechanisms to set missing terms (for example, “market price published by X on the day,” “average of three quotations,” or “good faith negotiation with expert determination if no agreement”). If you’re not ready for a binding contract, consider a non-binding MOU coupled with a binding exclusivity or confidentiality obligation.

Subject To Contract (Bridge Too Far)

Emails or heads of agreement that say “subject to contract” can indicate the parties don’t yet intend to be bound. That’s fine - until one party starts relying on the “deal” and discovers the other can walk away with no consequences.

How to fix: If you want an interim binding arrangement, state clearly which parts are binding (for example, confidentiality, exclusivity, break fee) and which are not, or move to a short-form contract now and expand later. Where you are still negotiating, a well-crafted Heads of Agreement can set expectations while clarifying what is and isn’t binding.

Termination For Convenience Without Consideration

Broad termination-for-convenience rights can be fair - but if one party can terminate immediately with no notice, fee or continuing obligations, their promise may be illusory.

How to fix: Include reasonable notice periods, termination fees where appropriate, payment for work in progress, or survival of key obligations (like confidentiality, IP licences and accrued payment rights).

Promises Dependent On Whim Or Wish

Language like “if we are satisfied,” “if we decide to proceed,” or “if we like the results” can be problematic if there’s no objective test.

How to fix: Replace subjective tests with objective ones (for example, “if the prototype achieves X performance measure,” or “subject to customer passing Y compliance tests”). If genuine subjectivity is required, consider an independent expert’s certification or a reasonableness standard.

Unlimited Price Variation Or Supply Flexibility

Clauses that allow one party to change prices or quantities at will risk illusoriness and UCT concerns in standard form contracts.

How to fix: Tie variations to objective inputs (CPI, exchange rates, raw material indexes) and require notice. Make sure there’s a right to terminate if the change materially impacts the deal. Where you’re supplying goods or services, strong, balanced Terms of Trade can hardwire fair variation mechanics.

How To Draft Enforceable, Non-Illusory Obligations

Here are practical steps you can take to turn vague “promises” into enforceable commitments that work commercially.

1) Define The Core Performance Clearly

• Specify what will be delivered, by whom and when.
• Use objective measurements where possible (quantities, timeframes, milestones, acceptance criteria).
• If some aspects are flexible, say which ones and set clear limits.

2) Add Minimum Commitments Or Mutuality

• If one party has flexibility, balance it with a minimum order, minimum monthly spend, or a genuine best efforts obligation tied to measurable outcomes.
• Where an option is granted (for example, exclusive distribution), ensure there’s real consideration (like an option fee or minimum commitment) so the promise isn’t illusory.

3) Use Objective Variation And Approval Mechanics

• Build mechanisms that set unresolved terms objectively (indexation formulas, third-party benchmarks, expert determination).
• Replace “sole discretion” on key performance terms with “acting reasonably” or “by reference to X benchmark.”

4) Limit Broad Termination And Discretion

• Include notice periods, cure rights, and fair termination-for-convenience fees to avoid a “promise today, no promise tomorrow” outcome.
• For price changes and service variations, require prior written notice and permit termination if changes are material.

5) Ensure Consideration Is Real

• Every promise should be supported by something of value in return.
• If a party’s “promise” boils down to “we’ll buy if we want,” add a non-refundable option fee, exclusivity fee, or minimum purchase that constitutes consideration.

6) Choose The Right Document At The Right Time

• If you’re not ready for a binding commercial contract, use a non-binding MOU with a few targeted binding clauses (like confidentiality) - and label it clearly.
• When you are ready to lock in the bargain, move to a signed contract so the essential terms are certain. If you’re still negotiating essentials, be careful before you rely on a “handshake” or email chain as a deal; a MOU can create clarity in the interim.

7) Draft Amendments Properly

• If something turns out to be too discretionary or vague after signing, you can usually fix it by formal amendment.
• Use a short amendment agreement or a Deed of Variation to tighten obligations, add objective criteria, or insert minimums. If you change a key term, be mindful of flow-on effects.
• Follow a clear process to amend a contract so the variation is valid and easy to evidence.

Practical Examples And Simple Fixes

Scenario 1: “We’ll Purchase Stock As Needed”

A reseller agreement says: “Buyer will purchase stock as needed.” If “needed” is up to Buyer with no minimums, Buyer might never order.

Fix: “Buyer will purchase a minimum of 200 units per quarter, and may place additional orders as needed. Forecasts are non-binding, but Buyer must act reasonably and cooperate on lead times.”

Scenario 2: “Payment Amounts Will Be Agreed Later”

A services agreement says: “Fees will be agreed each month.” If that’s essential and there’s no mechanism, you risk an unenforceable agreement to agree.

Fix: “Fees are set out in Schedule 1. For out-of-scope work, the parties will agree a fixed fee in writing. If they cannot agree within 10 business days, the fee will be the average of three quotes obtained from comparable providers.”

Scenario 3: “Supplier May Change Prices At Any Time”

Unchecked price variation can be both illusory (no real commitment) and unfair in standard form contracts.

Fix: “Supplier may vary prices on 30 days’ written notice no more than once per quarter. Variations are limited to increases in CPI or raw material input costs. Customer may terminate within the notice period if the increase exceeds 8%.” Balanced Terms of Trade can include these safeguards by default.

Scenario 4: “Subject To Contract” After Commercial Go-Ahead

The parties agree key deal points by email, start performing, but the email says “subject to contract.” If challenged, either party may argue there’s no binding agreement yet.

Fix options: Either (a) move quickly to an executed short-form contract capturing essentials, or (b) sign a binding short-form heads of agreement identifying which terms are binding now and providing a timeline for the long-form contract. If you’ve already started work, formalise the arrangement quickly to avoid a dispute over what was agreed.

Scenario 5: “We Can Cancel For Any Reason, Anytime”

A licence agreement says the Licensor can terminate immediately for convenience with no notice or fee. The Licensee invests heavily relying on the licence and is left exposed.

Fix: Insert a reasonable notice period (for example, 60-90 days) and survival clauses for accrued rights. If the licence is central to the Licensee’s business, consider a fixed term with limited termination triggers instead of broad convenience termination.

What Happens If A Clause Is Illusory? Remedies And Risk Management

If a clause is illusory, it may be unenforceable. Depending on how central it is, you may face a few outcomes.

Severance Or Reading Down

Where the rest of the contract can function without the problematic clause, a court may sever or read down the illusory part (especially if there’s a severability clause). This preserves the balance of the bargain where possible.

Implied Obligations Or Reasonableness

In some cases, courts may imply a duty to act reasonably or in good faith to save a clause from being illusory (for example, where discretion exists but needs limits to work commercially). Don’t rely on this; it’s better to draft the limits explicitly.

Consideration Fails

If the illusory promise is the consideration for the other party’s promise, the contract (or that part of it) can fail for lack of consideration. This is why it’s critical to ensure every core promise is real, not discretionary in the absolute sense.

Equitable Alternatives (Limited)

Even if a clause fails, a party may recover a reasonable sum for work done (quantum meruit) or rely on estoppel if they reasonably relied on a representation to their detriment. These are complex and fact-specific, so prevention through clear drafting is the better path.

UCT Risk In Standard Form Contracts

If you use standard form contracts with small businesses or consumers, broad unilateral discretion or termination rights can also be challenged as unfair under the Unfair Contract Terms regime. You can get support to review these risk areas through a targeted Unfair Contract Terms review, which focuses on balancing rights, transparency and necessity.

Fixing The Problem Post-Signing

Where you identify an illusory clause after signing, act quickly to regularise the arrangement. Record the intended obligations, insert clear objective tests, and ensure consideration supports both sides. A properly executed amendment or a Deed of Variation is generally the safest route.

Helpful Document Choices To Avoid Illusory Promises

Picking the right document type and structure will reduce the risk of illusory obligations from day one.

• Commercial Contract: A signed services or supply agreement with clear scope, pricing, timeframes and variation mechanisms protects both parties.
• Heads of Agreement: Useful to outline agreed essentials and (if you choose) bind specific clauses while you finalise the long-form deal.
• Purchase Orders + Master Terms: If you trade on repeat orders, use a master agreement plus POs that confirm quantities and timing against those terms.
• Terms Of Trade: For ongoing supply relationships, well-drafted Terms of Trade set defaults for pricing changes, delivery, acceptance, risk, and termination without overreaching discretion.
• Deeds For No-Consideration Obligations: If you need an obligation without consideration (for example, confidentiality during early talks), consider a deed - but still avoid vague, discretionary wording for critical promises.
• Amendments And Variations: When things change, use a formal process to amend a contract so your obligations remain certain and enforceable.

Quick Checks To Catch Illusory Promises Before You Sign

• Could either party choose not to perform the core obligation without consequence?
• Are key terms “to be agreed” later without an objective mechanism?
• Is pricing or quantity totally discretionary for one side?
• Are there broad termination-for-convenience rights with no notice or fee?
• Are approvals or satisfaction tests purely subjective with no benchmark?
• Has consideration been clearly exchanged for each promise - or should you use a deed?

If you answer “yes” to any of the above, refine the clause now. It’s easier to fix before signature than to argue about it later.

Related Contract Concepts To Keep In Mind

Illusory promises often pop up alongside other formation and enforceability issues:

• Offer vs Invitation To Treat: Make sure you have a real offer, not just an invitation to negotiate.
• Quotes And Binding Effect: A price indication alone may not be binding; whether a quotation is binding depends on context and terms, so confirm how your quote or proposal operates before it’s accepted.
• Verbal Agreements And Emails: Contracts don’t have to be formal to bind you. Emails and calls can create obligations - but vague language increases the risk of uncertainty or illusoriness.
• Heads Of Agreement And MOUs: If you’re not ready for a full agreement, a clearly labelled MOU or heads of agreement can help manage expectations and reduce misunderstandings while you negotiate.

Key Takeaways

• An illusory promise looks like a commitment but leaves one party free to do nothing, which risks unenforceability and lost consideration.
• Typical red flags include unlimited discretion, agreements to agree, “subject to contract” reliance, unrestricted price changes, and broad termination-for-convenience without safeguards.
• Draft around the risk by using objective criteria, minimum commitments, balanced variation and termination mechanics, and clear consideration.
• If a clause is already signed and looks illusory, tighten it with a formal amendment or a Deed of Variation and ensure the changes are properly executed.
• For standard form contracts, broad discretion or one-sided rights may also raise Unfair Contract Terms concerns - a focused UCT review can help.
• Choosing the right document - from Terms of Trade to heads of agreement - and documenting changes properly reduces disputes and protects your bargain.

If you’d like a consultation on reviewing or drafting your contracts to avoid illusory promises, you can reach us at 1800 730 617 or team@sprintlaw.com.au for a free, no-obligations chat.