What Is the Difference Between Detinue and Conversion?
A Detinue Arises When a Person Is Wrongfully In Possession of An Object That Should Be In the Possession Of Another Person and Despite Demands to Return the Object the Person With the Object Fails to Return the Object. With Conversion the Object Was Sold or Disposed and Return Is Impossible.
A Helpful Guide For How to Determine What Constitutes As the Tort of Detinue and What Differs From the Tort of Conversion
The tort of detinue is closely related to the tort of conversion. Indeed it seems that in certain situations there could be some overlap of elements of each tort; however, there are a few key unique nuanced differences, especially in respect of the options available for claiming damages, that deserve special attention and understanding.
The tort of detinue, including some of the nuanced differences. between detinue and conversion, was well articulated in Transit Trailer Leasing Ltd. v. Robinson, 2004 CanLII 19514 where it was said:
 To quote on the law of detinue, G.H.L. Fridman stated the following:
“The tort of detinue is closely related to, but is not the same as the tort of conversion. It may be defined as the wrongful or unlawful detention of another’s goods. Unlike conversion, it does not entail any denial of the plaintiff’s title. Conversion is a single act where the cause of action accrues at the date of the conversion. Detinue, however, is a continuing cause of action. It accrues at the date of the wrongful refusal to deliver up goods and continues until delivery up of the goods, or judgment in an action for detinue. An action for detinue will ordinarily only lie if, at the time of the demand for delivery up of the goods made by the person entitled to possession, the defendant was in actual possession.” G.H.L. Fridman, The Law of Torts in Canada, (Toronto; Carswell, 1989) at 95-6.”
 In reference to the comments of Linda Rinaldi on this subject, Remedies in Tort; supra, at 4-14, the requirement for demand in detinue she states:
The reason for the necessity of a demand for delivery before there can be liability in detinue is that the defendant may have acquired possession in ignorance of the plaintiff’s claim. The defendant must be given an opportunity to determine whether the claim is valid. Furthermore, because the goods are being sought, proof that the defendant is in possession of the goods is an essential element of the tort of detinue.
In both conversion and detinue, the defendant must commit an intentional and wrongful act in respect of the chattel. In an action for conversion, the wrongful act may take the form of any intentional dealing or interference with the chattel inconsistent with the rights of the person entitled to its possession. In act action for detinue the wrongful act consists of the wrongful withholding of the chattel.
As it appears upon review of the law of the tort of conversion and the law of the tort of detinue, a key nuanced difference is that the tort of detinue arises only upon failure to return property following a demand for return of the property. This requirement for a demand to return property, and where the cause of action is the 'failure' to do so, provides the nuance in detinue that the cause of action is a continuing cause of action. As a continuing cause of action, a case in detinue may provide for an eternal limitation period. Another key nuance is that a cause of action in detinue requires that the defendant be in possession, or control, of the property as is the subject of the demand to return. If the defendant is without possession, or control, of the property, such as having already sold or disposed of the property, a detinue case will fail and the appropriate cause of action is the tort of conversion.
Unique from the tort of conversion where the claim is typically for the value of the object wrongfully converted, in a detinue case the claim brought typically seeks the return of the object plus compensation for any loss by harm to the object while wrongfully held by the defendant. Additionally, claims for, essentially, a reasonable rental fee for the use of the object may be sought.
Disgorgement or Restitution
Alternatively, where the defendant benefitted from the use of the object for a profit or gain or to avoid a rental fee, in a detinue case claims may seek what are known as disgorgement damages, also sometimes referred to as restitution damages, which seek any profits or gains as monies earned from the use of the object. With this said, only one or the other form of damages may be claimed, either compensatory damages or disgorgement damages; however, generally, the choice will be made at the end of a trial; and accordingly, the option that presents the greatest benefit will be chosen.
 On the question of damages, following the concepts available to the plaintiff for election before judgment in pursuit of its claim within the period of unlawful and unauthorized possession of the plaintiff’s trailer, the remedy of restitution is available.
 It is in such a situation as presented here the authorities as taken from the common law confirm that where there is conversion, the victim of the tort has available alternative remedies, to waive the tort and sue in restitution, based on unjust enrichment.
 With such election the law of restitution provides in the granting of restitutionary relief that the defendant may be disgorged of any acquired benefit as a result of his wrongful act. In the alternative, the loss of benefit to the plaintiff should be recoverable within the same principle.
 It may well be that the end result whether in damages or restitutionary relief could be the same. In pursuit of the claim in either case, tort remains an essential aspect of the plaintiff’s cause of action. It is where the plaintiff waives the tort that the plaintiff may gain a number of procedural and substantive advantages in that he does not have to undertake the task of proving the exact value of the property converted and/or his specific loss, but rather relates it to the wrongful benefit received by the defendant and/or the loss to the plaintiff. The common law of England has in such situations allowed recovery for the use of a chattel even if the trailer could not have been leased during the unauthorized possession. (Strand Electric & Engineering Company v. Brisford Entertainment Company, 1952 All E.R. 796 (C.A.).
 Of importance to the plaintiff in its election as to the remedy for the loss caused by the tort is that the plaintiff’s election of its remedy in pursuit of damages is not required until the plaintiff seeks judgment.
This option, of either compensatory damages or disgorgement damages, enables the law to provide a discouragement to those who may otherwise commit the tort of detinue for a gain such as taking wrongful possession of an object, using the object for some form of gainful purpose, and then returning the object unharmed to the plaintiff. This reasoning was explained well in the Transit Trailer Leasing case where it was said:
 This principle is set out by Lord Denning in Strand Electric where his Lordship on the facts of that case had this to say:
If a wrongdoer has made use of goods for his own purposes, then he must pay a reasonable hire for them even though the owner has, in fact suffered no loss. If a wrongdoer has made use of goods for his own purposes, then he must pay a reasonable remuneration as the price of his permission. The wrongdoer cannot be better off because he did not ask for permission. He cannot be better off by doing wrong than he would be by doing right. He must therefore pay a reasonable hire.
As indicated, there are options available regarding the manner of damages claimed and where the option chosen is for disgorgement or restitution, damages for compensation must be waived. In the past, this choice to receive the disgorgement or restitution, which is more aligned with the law of equities than the common law, was referred to as “waiver of tort”. Indeed, the term, "waiver of tort" is mentioned in the Transit Trailer Leasing case above; however, the Supreme Court in the case of Atlantic Lottery Corp. Inc. v. Babstock, 2020 SCC 19 recently stated that the term is a misnomer and improperly used whereas the term wrongfully suggests that "waiver of tort" is an independent cause of action. In Atlantic Lottery Corp, the Supreme Court clarified that "waiver of tort" is merely a choice in the manner of damages claimed as a remedy to a tort rather than a "waiver" of the tort. Specifically, the Supreme Court said:
 Where a tort was made out but the plaintiff chose to pursue a claim in assumpsit to recover the defendant’s ill‑gotten gains, the plaintiff was said to “waive the tort” (Edelman, at pp. 121‑22). Despite its early acceptance, however, the term waiver of tort was a misnomer. Rather than forgiving or waiving the wrongfulness of the defendant’s conduct, plaintiffs relying on the doctrine were simply electing to pursue an alternative, gain‑based, remedy (Edelman, at p. 122; see also United Australia, Ltd. v. Barclays Bank Ltd.,  A.C. 1 (H.L.), at pp. 13 and 18). The doctrine always operated as “nothing more than a choice between possible remedies”, and not as an independent cause of action (United Australia, at p. 13; Martin, at pp. 504‑5). That this is so is apparent from decisions of this Court, including Arrow Transfer Co. Ltd. v. Royal Bank of Canada, 1972 CanLII 135 (SCC),  S.C.R. 845 where Laskin J. (as he then was), for the majority on this point, held that the plaintiff’s claim for a gain‑based remedy was dependent on the tort of conversion having been completed (p. 877).
The tort of detinue involves the wrongful possession of, and failure to return despite demands to return, some object which is the property of another person. It is the continuing possession with failure to return the object that makes the wrongful conduct in the tort of detinue different from the wrongful conduct in the tort of conversion, whereas with the tort of conversion the wrongfully possessed object is, generally, sold or disposed of and therefore impossible or impractical to return. As above, there is also a difference in the way damages are determined in a detinue case versus a conversion case.
The torts of detinue, conversion, and trespass to chattels, are often confused whereas the lines between each can, and often do, cross depending on the circumstances. Legal practitioners and scholars could spend hours discussing the various interplay between these various torts, among other torts. As always, these pages provide merely a beginning.