Imagine seeing an advert that says:
“Use our product, and if you still get influenza, we’ll pay you £100.”
You use the product. You still get influenza.
So you go back to the company and ask for your £100.
Would you expect them to actually pay?
That is essentially what happened in Carlill v Carbolic Smoke Ball Company, a case from 1892 that still makes an important point about something we encounter almost every day: advertisements.
The Carbolic Smoke Ball Company advertised its product as a way of preventing influenza and other illnesses. The company went a step further. It promised to pay £100 to anyone who used the smoke ball as directed, yet still contracted influenza.
To make the promise look serious, the company even stated that it had deposited £1,000 with a bank as a demonstration of its sincerity.
Mrs Louisa Carlill saw the advertisement, bought a smoke ball and used it according to the instructions. She nevertheless contracted influenza.
Naturally, she asked for the £100.
The company refused.
And that is where things got interesting.
The company argued, among other things, that the advertisement was not really an offer. It was simply an advertisement, a promotional statement designed to encourage people to buy its product.
The court did not agree.
The Court of Appeal held that the advertisement could amount to a genuine offer. It was not necessary for Mrs Carlill to write to the company and formally say, “I accept your offer.” The company had made the offer to the public, and Mrs Carlill accepted it by doing exactly what the advertisement required.
In other words, she did not have to promise the company anything in return. Her actions were enough.
That is the part of this case I find particularly interesting.
We see advertisements every day. Companies tell us that their products will do this, that they will give us that, or that we will receive a reward if we meet certain conditions.
Most of us read these claims, smile, and move on.
And, of course, not every statement in an advert is a contractual promise. Businesses are allowed to advertise their products. Not every catchy slogan creates a legal obligation.
But Carlill shows that there is a line.
If a business makes a sufficiently clear promise and sets out specific conditions for receiving something in return, it may not be able to simply dismiss the promise as “just an advert” when someone actually does what was required.
That makes the case feel surprisingly modern.
Think about promotions on social media. A company posts: “Buy this product, tag three friends and stand a chance to win GH¢5,000.” Or perhaps: “Refer five customers and receive GH¢500.”
What happens when someone follows the instructions and the company suddenly changes its mind?
The answer will depend on the wording and circumstances. But Carlill reminds us that words matter. The fact that a promise appears in an advertisement does not automatically make it meaningless.
There is also a lesson here for consumers.
Sometimes we are quick to assume that the law is only concerned with complicated contracts filled with pages of legal language and signatures.
It isn’t always that complicated.
In Carlill, Mrs Carlill did not sit down with the company and negotiate a contract. She did not sign a document. She simply saw a promise, followed the stated conditions and expected the company to keep its word.
And perhaps that is why the case has remained so memorable.
A promise does not become less important simply because it was made to the public.
For businesses, the lesson is equally simple: be careful about what you promise.
If you put a clear promise in an advert, you should be prepared for someone to take you seriously.
After all, what is the point of telling people, “Do this and we will pay you,” if you never intended to pay when someone actually does it?
Mrs Carlill took the company at its word.
And, eventually, the court did too.
Story by Adwoa Serwaa Danso
(Ghana School of School, BL Candidate)