The principle of legality in statutory interpretation has a long history in Australian law, stretching back to the High Court case of Potter v Minahan in 1908. In Electrolux Home Products Pty Ltd v AWU, Gleeson CJ spoke of the principle of legality as a working hypothesis between Parliament and the courts, and an aspect of the rule of law. The courts were not to impute an intention to "abrogate or curtail certain human rights or freedoms unless such an intention is clearly manifested". Recent High Court decisions suggest that members of the new bench do not share the former Chief Justice's high reverence for the principle, and that the Court's previous insistence on unambiguous language to curtail fundamental rights may be waning.

Development of the principle of legality

As legislation increasingly infiltrated areas previously the domain of the common law during the twentieth century, the courts staged a rear guard action to defend the legacy of the law developed by judges over centuries. Various rights, described either as fundamental or vulnerable, mostly emanating from the common law, were "protected" by a requirement imposed by the courts that Parliaments exhibit a clear intention to override them: no general words would be enough for the courts to find an intention on the part of the legislators to push those rights aside. This was described as the "principle of legality", or at other times, the "clear statement principle".

Although posed as representing the intention of Parliament, in many cases the actual intention of those bringing the legislation into effect had little or no bearing on the approach of the courts. In Coco v The Queen, it was represented as a matter of principle: "[t]he courts should not impute to the legislature an intention to interfere with fundamental rights" and "curial insistence on a clear expression of an unmistakable and unambiguous intention to abrogate or curtail a fundamental freedom will enhance the parliamentary process".

The first real flaw with this "principle of legality" was that the weight of experience showed that legislators did in fact intend to modify, adjust and, in some cases, remove rights that had previously been enjoyed under the common law. That the courts, in reality, only gave passing reference to the intention of the legislators meant that this could only cause a glancing blow to the principle of legality.

The growing importance of the words of the statute

A more serious blow to the principle of legality has been dealt with the growing attention to the text in discerning legislative intention. Consistent with the seminal decision in Project Blue Sky, the focus is still on understanding the purpose of a statute as a means of interpreting its discrete parts. However, the emphasis more recently has been on finding the purpose within the text itself. Hence, in Certain Lloyd's Underwriters Subscribing to Contract No. IH00AAQS v Cross, it was said that "[t]he purpose of a statute resides in its text and structure" and in Lacey v Attorney-General of Queensland, "[t]he purpose of a statute is not something which exists outside of the statute".

Importantly, this appears to have led some members of the current High Court bench to approach questions of the exclusion of fundamental rights in a different way: rather than identifying the relevant right or principle and looking for clear words excluding it, some have instead started with a construction of the text and then asked the question of whether there remains any "space" for the recognition of the relevant right or principle. The clearest examples of this approach can be seen in Plaintiff S10/2011 v Minister for Immigration and Lee v NSW Crime Commission.

Prior to Plaintiff S10/2011, in Saeed v Minister for Immigration and Citizenship, five members of the High Court emphasised the fundamental nature of natural justice and the need for clear expression of an intention to exclude or limit those requirements. They emphasised that the clear intention had to be found in the statute, and not extrinsic materials, no matter how clear and emphatic statement in such materials might be. Therefore, even clear words that attempted to exclude the obligations of natural justice were read restrictively so as not to apply in the circumstances of that case.

However, in Plaintiff S10/2011 there was a sufficiently clear legislative intention to exclude the obligations of procedural fairness, despite the absence of express words to that effect. This intention was derived from the cumulative effect of several structural features of the statutory scheme, including the prior hearing provided to the applicants, the lack of any obligation on the Minister to consider the applications and the need to table in Parliament any decisions to grant the visas in question.

A similar comparison can be made between the decision in X7 v Australian Crime Commission and the decision that followed in Lee. Both cases concerned questioning powers in criminal-related matters, and whether those powers could be exercised where the person being questioned had been charged with a criminal offence.

In X7 and Lee there was considerable disagreement between the various judges on the application of the principle against self-incrimination. In X7, a majority found that the questioning power could not be used to require answers from a person who had been charged with an offence.

In Lee, Gageler and Keane JJ, who were the only judges who did not sit on the X7 case, turned the tables. After referring to the role of context in applying the principle of legality, their Honours recognised that there may be "legitimate legislative judgments that, for compelling reasons of public interest," lead to an interference with the rights or advantages in question:

"The interpretative strictures of the legality principle should not be applied so rigidly as to have a sclerotic effect on legitimate innovation by the legislature to meet new challenges to the integrity of the system of justice."

We are yet to see whether the High Court continues down the path begun by Plaintiff S10/2011 and Lee. For now, at least, these cases appear to mark an important turning point in the principle of legality.

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