9. Flexible terms

This chapter considers how parties try to build flexibility into their contracts, along with the legal hurdles they face. A contract, or contractual clause, is vague if the words the parties have chosen give no real way of deciding what the parties are required to do and whether they have done it. A contract is incomplete if it fails to deal with a matter which is so fundamental that the transaction cannot be performed without agreement being reached on it. The effect of vagueness and incompleteness is to render the clause or contract void in law. Vagueness and incompleteness are often said to be closely related to the requirement of certainty in contracting, which crops up in a number of different areas of contract law. This chapter first discusses certainty and the complex transaction, along with vagueness and open-ended clauses, before turning to incompleteness and agreements to agree.