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What is a Unilateral Contract? (2019 Update)

What is a Unilateral Contract? (2019 Update)

Learn about what makes a unilateral contract different to bilateral contracts and how it can be a great marketing tool for small businesses.

25th July 2019

Contracts may seem pretty straightforward – two people (or businesses) discuss making a deal of sorts, and one in which is mutually beneficial. They then agree on the terms and shake hands to seal the deal. However, contracts can take more forms than a simple handshake. A unilateral contract is a good example of this. In this article, we’ll explain what a unilateral contract is and the legal ramifications involved.

Establishing a legally binding contract

To ensure a contract is legally binding, there are four major elements that must exist:


One party needs to present an offer which is accepted by the other. In agreeing on terms, there must be no coercion or duress on either side.


There needs to be a price or liability paid for the promise. However, consideration does not always have to be monetary. For example, if you’re selling your car, you can accept shareholdings or other property of the purchaser as payment. This will also constitute consideration.

Intention to create legal relations

There needs to be an intention for the contract to be legally binding. Each party to the contract should understand what they’re signing up to and what their legal obligations will be upon signing the contract.


The contract needs to be sufficiently clear and complete.

The fundamental backbone of a contract is an agreement, consisting of an offer by one party and acceptance by the other. What makes unilateral contracts unique is the way in which an agreement is formed.

Unilateral contracts

When most people think about a contract, they are most likely thinking of a bilateral contract where the two or more parties enter into a mutually beneficial agreement. Learn more about Bilateral Contracts to further understand the difference. Unilateral contracts are by contrast, one-sided.

A unilateral contract is a legally binding contract in which an offer is accepted by fulfilling the relevant condition/s. Unlike bilateral contracts where there is an exchange of mutual promises, only one party in a unilateral contract makes an express promise. They are then obliged to perform the promise.

A common example occurs when “Person A” places an advertisement that states that if someone finds their lost dog and returns it to them, then “Person A” will pay that party $100. Only “Person A” has made an express promise. If “Person B” finds and returns their lost dog, then “Person B” has fulfilled the condition posed by “Person A”, thereby accepting the offer. A unilateral contract is thus formed.

Another example would be a burrito stand which runs a burrito-eating competition. The burrito stand promises that whoever eats the highest number of burritos in 2 minutes will receive a $200 voucher. Although multiple people are ‘entering’ into this contract, only one will fulfil the condition which will activate the promise held within the contract.

Unilateral contracts for small businesses

Consumers or parties are sometimes hesitant to enter into a contract with small businesses. However, due its one-sided nature, unilateral contracts have a variety of uses that can be used to grow your business.

Firstly, unilateral contracts can be used to establish loyalty of consumers through a rewards system. Many cafes or coffee stands hand out cards to customers which entitle them to their tenth (or fifth) coffee free. This common marketing technique utilises the reward system. This will incentivise consumers to remain with your business or product – thereby assisting in your own business’ growth.

Secondly, unilateral contracts can promote awareness of your business. A prime example today is the Killa Burger Challenge. The promise from Killa Burger Grill was that if you eat a Killa Burger (30cm wide), Wicked Chips, Killa Drink (1.25L) and a Killa Soft Serve alone in 60 minutes, you will receive some ‘Killa’ prizes and your name on the ‘Wall of Fame’. This promotional challenge and campaign is also a unilateral contract, with Killa Burger Grill promising the prizes to those that complete the challenge.


Unilateral contracts may at first sound one-sided or unfair. However, unilateral contracts are one the most common types of contract a business will use. This is because it will not only benefit your business, but also your customers. After all, your customers wouldn’t sign up to a unilateral contract if there was no potential benefit. If you’re unsure what terms to include in you unilateral contract, it is worth consulting with a business lawyer for further advice. 

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Jackie Olling

Jackie is the Content Manager at Lawpath and manages the content team. She has a Law/Arts (Politics) degree from Macquarie University and is an admitted solicitor in the Supreme Court of NSW. She's interested in how technology can help shape the future legal landscape.