Extrinsic materials, such as second reading speeches and explanatory memoranda, can be helpful but should be used with care. This case (at [144-148]) notes that extrinsic materials may help you find the purpose or object of a provision3, although this must also be supported by the words of the statute4.
However, extrinsic materials cannot alter the meaning of words in a provision if this is clear on their face5. You can only consider extrinsic materials when determining a provision’s meaning if it is ambiguous or obscure or would create an obviously absurd result6. iTip – yes, always consider extrinsic materials, but know their limitations.
This case is from Episode 15 of interpretationNOW!
3 K-Generation  HCA 4 (at ).
4 Harrison  NSWCA 67 (at [12-16]).
6 Acts Interpretation Act 1901 s 15AB(1)(b).