Duplicity occurs where one charge alleges more than one offence. Double punishment occurs where two (or more) offences describe the same act. Both are errors in legal drafting that can result from trying to apply neat legal theory to untidy real life events.
Since duplicity and this particular sub-set of double jeopardy involve matters of fact and degree it’s not easy to say with confidence when an offender is doubly punished and when they aren’t. A review of the case law resists the expression of a general rule. McHugh, Callinan and Hayne JJ said in Pearce v R (1998) 194 CLR 61 [at 40] that the sentencing judge should use common sense. That’s not a test likely to be applied consistently.
The High Court was echoing Lord Morris of Borth-y-Gest in DPP v Merriman (1973) AC 584, who said [at 593],
The question arises – what is an offence? If A attacks B and, in doing so, stabs B five times with a knife, has A committed one offence or five? If A in the dwelling house of B steals ten different chattels, some perhaps from one room and some from others, has he committed one offence or several? In many different situations comparable questions could be asked. In my view, such questions when they arise are best answered by applying common sense and by deciding what is fair in the circumstances. No precise formula can usefully be laid down but I consider that clear and helpful guidance was given by Lord Widgery C.J. in a case where it was being considered whether an information was bad for duplicity: see Jemmison v Priddle  1 Q.B. 489, 495. I agree respectfully with Lord Widgery C.J. that it will often be legitimate to bring a single charge in respect of what might be called one activity even though that activity may involve more than one act. It must, of course, depend upon the circumstances.
Tran v The Queen  VSCA 363 is a recent example. The appellant was sentenced for offences of reckless conduct and assaulting police officers arising from the same incident. On the appeal he argued that R v Sessions  2 VR 304 stood for the proposition that he should not have received a penalty for each charge.
Nettle JA described the tense events leading to the charges this way [at 7],
The appellant was under surveillance by the Special Operations Group. Police watched the appellant exit a house in St Albans and enter the driver’s seat of a Commodore.
Police vehicles then attempted to intercept the appellant. A white police van pulled up beside the appellant’s car and another police vehicle activated its siren. Hearing the siren, the appellant repeatedly rammed a red sedan parked in front of his car until an avenue of escape was created and then accelerated down the street, colliding forcefully with a green four-wheel drive police vehicle which blocked his escape. Once the appellant’s vehicle was stationary, Operator 55 (a policeman) opened the door and grabbed the appellant’s shoulder shouting, ‘Police, don’t move.’ But the appellant struggled free and reversed rapidly causing the driver’s door to hit Operator 55’s lower left leg. The impact forced Operator 55 backwards until he collided with Operator 78 (another policeman) knocking him to the ground. Operator 55 sustained bruising and swelling of his left lower leg and Operator 78 landed heavily on his right elbow and sustained minor grazing and soreness (Charges 5 and 6, assault police).
The appellant reversed past the white police van, shearing off the door. He continued, hitting another unmarked police vehicle and a power pole guide wire on the nature strip. Then he accelerated forward along the footpath. The green four-wheel drive collided with the appellant’s car as he drove along the footpath, forcing his vehicle into a fence. Operator 96 (another policeman) was struck by the appellant’s vehicle and lifted from the ground into the fence. (Charge 4, reckless conduct endangering life).
The appellant attempted to flee on foot and was tasered. He got back into his car, however, and was tasered again before finally being arrested. Then he was taken to the police station.
It was suggested that it was artificial to draw a distinction between the driving that impacted directly on the police officers and the rest of the driving that placed other (or potential) road users at risk. The argument was ultimately unsuccessful.
Nettle JA [at 20]:
Nor in my view is there anything illusory or artificial about the way in which the Crown drew a distinction between the specific acts of delinquent driving which constituted the assault of Operators 55 and 78 (which is to say, accelerating backwards into Operator 55 as he attempted to arrest the appellant) and the balance of the appellant’s delinquent driving which recklessly endangered the lives of others (by repeatedly ramming the red sedan; accelerating down the street so as to collide forcefully with the green four-wheel drive police vehicle blocking the appellant’s escape; reversing past the white police van, thereby shearing off its door; continuing on and hitting another unmarked police vehicle and a power pole guide wire on the nature strip; and finally accelerating forward along the footpath into a further collision with the green four-wheel drive, hitting Operator 96, and ultimately careering into the fence).
It is true that the Chief Judge referred in his sentencing remarks to ‘the driving’ constituting the offence the subject of Count 4. Perhaps, his Honour could have been more precise in his description of the offence. But, with respect, it is plain what his Honour intended. And, in view of the Plea Opening, there could not have been any doubt about it. It was the Plea Opening which was taken to set forth the facts agreed for the purposes of the plea and there is no reason to doubt that it was that which his Honour intended to encapsulate in the short hand form of expression which he adopted.
The appellant didn’t challenge a charge being laid for each of the two police officers involved, even though it was really one act that was said to make out the assault against both. Multiple charges, each alleging a separate victim, have always been permitted as an exception to the general rule: R v WWS  VSCA 125 [at 30].