As the threat must be to "inflict" serious injury rather than "cause" serious injury, it is unclear whether a threat to cause serious injury will always be covered by this offence. "Cause" is generally thought to be a wider term, that includes "inflict" (see R v Salisbury  VR 452; R v Mandair  1 AC 208; R v Ireland & Burstow  AC 147).
While the prosecution must prove that the complainant received the threat, s/he need not be the person threatened. The accused may have threatened to inflict serious injury upon another person (Crimes Act 1958 s21).
It is not necessary that the complainant have any particular relationship with the person threatened. This element will be satisfied even if the accused threatens to inflict serious injury upon someone that the complainant does not know (R v Solanke  1 WLR 1; R v Syme (1911) 6 Cr App R 257).
It is not necessary that the accused threaten to personally injure the complainant or other person. The threat may be to have someone else carry out the assault (Barbaro v Quilty  ACTSC 119).
A threat can be conditional on the occurrence of a future event. It is not necessary that the accused have the immediate capacity or intention to carry out the threat (R v Leece (1995) 125 ACTR 1; Barbaro v Quilty  ACTSC 119).
How Can a Threat be Made?
A threat can be made by words or conduct or both (R v Rich Vic CA 17/12/1997).
A threat can be made in writing and delivered or left with another person. The threat does not have to be received at the same time that it is made (R v Jones (1851) 5 Cox CC 226).
It is not necessary for the prosecution or the judge to identify the precise words or conduct that constituted the threat. Where the accused acted in a continuously threatening and abusive manner, the jury may consider whether his or her conduct as a whole amounted to a threat (R v Rich Vic CA 17/12/1997).
Impact of the Threat
It not necessary for the prosecution to prove that the complainant feared that the threat would be carried out, nor is it sufficient for the prosecution to prove that the complainant did feel such fear. (R v Rich Vic CA 17/12/1997; R v Alexander  VSCA 178).
In making its determination, the jury must consider the relationship between the accused and the complainant. Violent or colourful language that may appear threatening at first sight, may in fact not be a "threat" when the relationship is taken into account. For example, it may be clear, in the context of the parties’ relationship, that the accused did not intend to move beyond heated words and gestures (Barbaro v Quilty  ACTSC 119).
The Accused’s State of Mind
The second element requires the accused to have either:
Intended the complainant to fear that the threat would be carried out; or
Been reckless as to whether or not the complainant would fear that the threat would be carried out (Crimes Act 1958 s21).
It is not necessary for the accused to have intended to carry out the threat. The only issue is whether the accused intended the complainant to believe that the threat would be carried out (R v Alexander  VSCA 178; Barbaro v Quilty  ACTSC 119).
The motive for making the threat is irrelevant (R v Solanke  1 WLR 1).
To establish the requisite intention, all of the circumstances of the statement or conduct must be considered (R v Leece (1995) 125 ACTR 1; R v Alexander  VSCA 178).
To have been reckless as to whether or not the victim would fear that the threat would be carried out, the accused must have been aware, when s/he made the threat, that it was probable that the complainant would fear that it would be carried out (R v Crabbe (1985) 156 CLR 464; R v Sofa Vic CA 15/10/1990).
The accused must have been aware that it was "probable" or "likely" that the complainant would fear that the threat would be carried out. It is not sufficient for him/her to have been aware that this fear was merely "possible" or "might" result (R v Crabbe (1985) 156 CLR 464; R v Campbell  2 VR 585; R v Nuri  VR 641).
The accused him/herself must have been aware that the complainant would probably fear that the threat would be carried out. It is not sufficient that a reasonable person in the accused’s circumstances would have realised that the complainant would probably fear the threat (R v Sofa Vic CA 15/10/1990; c.f. R v Nuri  VR 641).
It is not appropriate to invite the jury to apply their normal understanding of the meaning of "recklessness". Conventional understanding of the term may include conduct that is negligent (Banditt v The Queen (2005) 224 CLR 262).
When explaining recklessness to the jury, it is common for judges to require them to also find that the accused was indifferent to the consequences of his or her conduct (see, e.g., R v Sofa Vic CA 15/10/1990; R v Nuri  VR 641; R v Campbell  2 VR 585; R v Wilson  VSCA 78).
While the abovementioned authorities suggest that an indifference to consequences is an independent element of recklessness at common law, there is strong authority for the proposition that an awareness of the probable consequences of conduct is all that is required (R v Crabbe (1985) 156 CLR 464).
Threat Made Without Lawful Excuse
The threat to inflict serious injury must have been made without any lawful justification or excuse (Crimes Act 1958 s21).
Self-defence and prevention of crime are common forms of justification in this area (R v Cousins  1 QB 526).
A person acts in self defence when s/he believes, on reasonable grounds, that his/her actions are necessary (Zecevic v DPP (Vic) (1987) 162 CLR 645. See Common Law Self-Defence).
A person may justifiably make a threat to inflict serious injury in circumstances where it would not be reasonable to carry out that threat. A threat is a lesser form of harm than the execution of the threat (R v Cousins  1 QB 526).