The overarching principle is that the contract is frustrated because performance would now be 'radically different' from that which was contracted for. However, performance may be radically different for a number of reasons, three of which will be considered in this chapter. First, performance is impossible, second, performance is illegal or prevented by government intervention, and third, the common purpose of the contract is frustrated. It is important to note that this list of categories is not exclusive nor will all frustrating events fit neatly into one category or another.