The highly publicised case that the BBC brought last year to keep the identity of the Stig secret is another illustration as to why contracts need to be carefully written.
As we all now know, Ben Collins has been identified as being the Stig between 2003 and 2010. He was outed after the case where the BBC attempted to stop HarperCollins publishing Collins' autobiography, 'The Man in the White Suit'.
The problem for the BBC is that they had contracted with Collins' company, Collins Autosport, to provide Ben Collins for the role of the Stig and not Ben Collins himself even though Collins had signed on behalf of his company. In other words, the company - Collins Autosport - owed the duty of confidence to the BBC but Ben Collins was under no such obligation. Further, the BBC didn't establish a link between Collins Autosport and the publication of the book.
The lesson to be learned is simple. If you want someone or a company to be bound by a contract you need to ensure that they (or it) are named on the contract and have signed it. You also need to ensure that you determine if a person, the company, or both, are to be bound by whatever obligations you consider relevant.