The subject of statutory interpretation is important because much of New Zealand law is contained in the statute books and because the majority of legal issues that come before the courts involve statutory interpretation .Professor John Burrows "The Changing Approach to the Interpretation of Statutes"
[In 1996, sixty-four percent of cases in the Court of Appeal involved statutory interpretation . See Jane Allen " Statutory Interpretation and the Courts" (1999) 18 NZULR 439, 440. .] Issues of interpretation arise because the precise meaning of words is often uncertain. There is usually an inner core of meaning that all reasonable people would agree upon and also a vast world of meaning that is clearly not conveyed by the word. However, there is a murky area in between these two spheres where interpretation becomes more difficult. The case of Kecold Ltd v O'Brien [Kecold Ltd v O'Brien  3 NZLR 261 (CA).] illustrates the uncertainty at the outer edges of meaning. This case involved interpretation of the word "sick". The inner core of meaning of this word is clear. If a person has influenza, cancer or food poisoning, for example, their condition is clearly within the meaning of "sick". The Court of Appeal had to decide whether the word "sick" applied to a person who was injured.[ The Court concluded that the word "sick" in the context of the Holidays Act 1981 could apply to a person who was injured.]
The meaning of some words is particularly uncertain, in that the very nature of the word involves an element of subjectivity. For example, the Consumer Guarantees Act 1993 requires that goods supplied to consumers must be of "acceptable" quality, and the Credit Contracts Act 1981 prohibits "oppressive" credit contracts. Other statutes require the Court to make such orders "as it thinks just".[See, for example, the Contractual Mistakes Act 1977 s 7(3) and the Contractual Remedies Act 1979 s 9.]Where such broad and non-specific wording is used, the courts must use their discretion to determine the scope of the words. If the provision comes before the court enough, an important body of case law will develop to fill out the meaning of the provision.