Finally, problems of agreement sometimes arise because a contract of requirement prohibits the buyer from doing business with a given good with a party other than the seller. This can become an exclusive negotiation agreement that gives the seller monopoly power over the buyer and prevents the buyer from seeking better activity if the market becomes more competitive. Conversely, a buyer capable of generating sufficient demand can absorb the seller`s overall performance and effectively deter that seller from competing with the free market. Nevertheless, the requirement contracts were maintained due to problems with the agreements.  In The Antitrust Paradox, Robert Bork examines demand contracts and argues that they are not anti-competitive precisely because they are a product of freedom of contract. Contracts must have sufficiently defined terms to allow a court to determine where an offence occurred. It would be difficult to determine whether, in a contract of needs, the buyer incorrectly claims that his needs are lower than he really is, in order to renegotiate or cancel the contract. Conversely, if market conditions make the contract price a boon for the buyer, that buyer may decide to buy more than they actually need to compete with the seller. Courts often look at the history of transactions between the parties and the standards within the industry, in order to determine whether the buyer is acting in bad faith in the event of a breach of contract on demand contracts. . . .