In Victoria the Act defines a drug as [at s 4]:
drug of dependence means a substance that is-
(a) a drug-
(i) specified in column 1 of Part 1 of Schedule Eleven; or
(ii) included in a class of drug specified in column 1 of Part 1 of Schedule Eleven; or
(b) any fresh or dried parts of any plant specified in column 1 of Part 2 of Schedule Eleven; or
(ba) prescribed as a drug of dependence in accordance with section 132AA whether specified as included in Part 1, Part 2 or Part 3 of Schedule Eleven; or
(c) a drug-
(i) specified in column 1 of Part 3 of Schedule Eleven; or
(ii) included in a class of drug specified in column 1 of Part 3 of Schedule Eleven- and includes-
(d) any form of a drug specified in column 1 of Part 1 or column 1 of Part 3 of Schedule Eleven, whether natural or synthetic, and the salts, derivatives and isomers of that drug and any salt of those derivatives and isomers; and
(i) drug specified in, or drug included in a class of drug specified in column 1 of Part 1 or column 1 of Part 3 of Schedule Eleven, whether natural or synthetic; or
(ii) salts, derivatives or isomers of a drug specified in column 1 of Part 1 or column 1 of Part 3 of Schedule Eleven; or
(iii) salt of any derivative or isomer mentioned in subparagraph (ii)- contained in or mixed with another substance; end user declaration means a declaration required for the purposes of section 80J, 80L or 80M, as the case requires;
The Act doesn't provide a definition of what the terms salts, derivatives and isomers mean.
The Commonwealth Criminal Code refers to drug copycats as analogues. The definition of analogue is found at s 314.1(2) for controlled drugs and s 314.4(2) in the case of border controlled drugs.
(Please note that, although I've linked to the Code on AustLII, I don't recommend opening it unless you really need to. AustLII's automated bots are incapable of handling the Commonwealth parliament's predelicition for placing enormous schedules - often bigger than the Acts they're attached to - like the Criminal Code and Australian Consumer Law in the back of their Acts. To access one provision in a schedule at AustLII it's necessary to download the lot. If you're after a more printer-friendly version, use ComLaw).
The definition of analogue for both categories of drug is extensive. Sub-section 314.1(2) reads,
(2) A substance is a controlled drug if the substance (the drug analogue ) is, in relation to a controlled drug listed in subsection (1) (or a stereoisomer, a structural isomer (with the same constituent groups) or an alkaloid of such a controlled drug):
(a) a stereoisomer; or
(b) a structural isomer having the same constituent groups; or
(c) an alkaloid; or
(d) a structural modification obtained by the addition of one or more of the following groups:
(i) alkoxy, cyclic diether, acyl, acyloxy, mono-amino or dialkylamino groups with up to 6 carbon atoms in any alkyl residue;; or
(ii) alkyl, alkenyl or alkynyl groups with up to 6 carbon atoms in the group, where the group is attached to oxygen (for example, an ester or an ether group), nitrogen, sulphur or carbon;
(iii) halogen, hydroxy, nitro or amino groups
(e) a structural modification obtained in one or more of the following ways:
(i) by the replacement of up to 2 carbocyclic or heterocyclic ring structures with different carbocyclic or heterocyclic ring structures;
(ii) by the addition of hydrogen atoms to one or more unsaturated bonds;
(iii) by the replacement of one or more of the groups specified in paragraph (d) with another such group or groups;
(iv) by the conversion of a carboxyl or an ester group into an amide group; or
(f) otherwise a homologue, analogue, chemical derivative or substance substantially similar in chemical structure;
however obtained, except where the drug analogue is separately listed in subsection (1).
It might be that the Commonwealth legislation is just more specific than the Victorian provision, but the general consensus is that the term analogue covers more than salts, derivatives and isomers.
In DPP (Cth) v Coory the substance was methylmethcathinone. The accused was charged with importation of a border controlled drug under s 314.4 of the Criminal Code, and pled guilty.
Methcathinone (also known as miao miao) is a substance which is thought to simulate the effects of MDMA or amphetamine. It's specifically prohibited in Victoria by its inclusion in Schedule 11 of the Drugs, Poisons and Controlled Substances Act 1981 and s 314.4(1)(95) of the Criminal Code. Methylmethcathinone isn't specifically mentioned in either the state or Commonwealth schedules, but has a similar chemical structure to methcathinone.
In Victoria it's settled that all drugs of dependence are treated on sentence as being equally harmful. If parliament intended different drugs of dependence to attract different penalties, the reasoning goes, parliament would have allocated different penalties to them, rather then putting them all in the one penalty section: R v Adams (2008) 234 CLR 143; R v Pidoto & O'Dea (2006) 14 VR 269, both referred to here. Though this rationale might fly in the face of experience, the High Court approved it on the basis that if this wasn't the law then sentencing hearings would bog down in non-justiciable arguments about whether amphetamine is more dangerous than heroin, cocaine use more prevalent than ecstacy use, etc.
Among the sentencing judge's remarks was a comment that the harm caused by methylmethcathinone is unclear. While both factually correct and made in the context of condemning the accused's behaviour, on the DPP appeal the Crown asserted that this comment reflected the judge engaging in an assessment of the harm caused by a particular drug of dependence.
Harper JA [at 27]:
27 The argument in its favour is based in part upon references in her Honour’s reasons for sentence to the similarity, in some respects, of 4-MMC to other designer stimulants. Her Honour also referred to its use as an alternative for amphetamine related drugs and MDMA (or ‘ecstasy’). Then the judge said:
In terms of the harm your offending caused or could have caused, [it] is unclear what harm the drug 4-MMC causes. Fortunately, the authorities detected you and your offending was stopped. Due to the vigilance of customs officials, this clearly stopped further amounts of these drugs getting into the community. The custom’s vigilance, of course, comes at the expense and inconvenience of the Australian community as a whole.
The appellant submits that error is revealed by the references to other designer stimulants, to the use of 4-MMC as an alternative for both amphetamines and ecstasy, and to the harm caused by 4-MMC. I agree with these submissions. The Director points, correctly, to authorities which establish that, in sentencing for drug offences, it is impermissible to apply ‘a judicially constructed harm-based gradation of penalties’. I depart from him, however, when he goes on to submit that the sentencing judge drew an inference favourable to the respondent from the absence of any specific evidence of harm caused by 4-MMC.
The appellant submits that the drawing of such an inference is evidenced by her Honour’s observation in her reasons for sentence that it was not clear what harm the drug caused or could cause. So far as I can see, however, there is (apart from the impugned passage) nothing in those reasons for sentence to suggests that she took into account as a mitigating factor any notion that the relative harm suffered by consumers of 4-MMC, and the general public which must share the cost of its use, was less than for other illicit drugs. Indeed, during the course of argument on the plea, her Honour made it quite clear that she was aware that, in her words, ‘an illicit drug is an illicit drug, it doesn’t matter whether it is heroin or marijuana.’
Both Redlich JA [at 8] and Harper JA [at 46] remarked on the desirability of removing the doubt surrounding the status of 4-MMC as a drug of dependence under the Victorian Act, by an appropriate amendment to the Drugs, Poisons and Controlled Substances Act 1981 to make drug copycat legislation work the same way at state and federal level.
Edit: Parliament haven't yet signalled any intention to act on this advice, but a couple of months ago they did pass the Drugs, Poisons and Controlled Substances Amendment (Drugs of Dependence) Bill 2011. This bill allows the addition of new substances to the schedule through regulation, rather than legislative change.