Research paper on contract law: carlill v carbolic smoke ball co. Needs to be 5 pages. The advertisement which Kelly has placed in the local newspaper is an offer that has been made to the world at large, such as for example in the case of Carlill v Carbolic Smoke Ball Co.3 A mere offer will only constitute a unilateral contract, which will also be deemed valid only if some party proffers an unconditional acceptance of the terms of the offer.4 John has seen the advertisement in the paper and has posted his acceptance to Kelly. However as McKendrick states, for a contract to be valid, “there must be a definite offer mirrored by a definite acceptance.”5 Acceptance will be said to occur when the offeree’s words or conduct can give rise to an objective reference that he/she has assented to the terms offered.6 On this basis, Kelly’s advertisement in the paper constitutes a definite offer and John’s reply constitutes acceptance of the terms of the offer. In the case of Gibson v Manchester City Council, it was held that the acceptance of the offer must also be communicated before it can be valid on a contractual basis.7 According to Lord Denning, no contract will come into existence unless and until the acceptance has been communicated to the offerer8. Therefore, if a contract is to exist between Kelly and John, then Kelly should have received John’s acceptance of her original offer, without any changes in its terms. John has indeed accepted the offer as per its original terms and since John’s acceptance of the offer has been sent by post then it will be held to be a valid acceptance as soon as he posted his letter.9 In fact, the courts have held that where a postal. acceptance is concerned, it will hold good even in those instances where the letter is delayed or lost in the post so that it never reaches the offerer.10 However, an offer cannot be accepted by the offeree unless and until the offer is communicated to him/her and silence.