Irreparable harm is the second part of the usual test for a conventional interlocutory injunction. “Irreparable” refers to the nature of the harm, not simply its size. The question is whether the harm can be adequately compensated with money or otherwise effectively remedied later if the moving party ultimately succeeds.
The Supreme Court of Canada explained this principle in RJR—MacDonald Inc. v. Canada (Attorney General). The focus is on whether refusing interim relief could affect the applicant’s interests in a way that a later judgment would not adequately repair.
For the complete framework, see What do you have to prove to get an interlocutory injunction in Ontario?.
Does financial loss count as irreparable harm?
Ordinary financial loss will not usually amount to irreparable harm where it can be calculated and adequately compensated through damages after trial.
A large financial loss is therefore not automatically an irreparable one.
The analysis can be different where the loss cannot realistically be quantified, where compensation cannot practically be recovered, or where the consequences extend beyond an ordinary measurable monetary loss.
Depending on the circumstances, alleged harm may involve permanent market loss, serious damage to a business relationship or reputation, disclosure or misuse of confidential information, loss of a unique commercial opportunity, or another consequence that cannot readily be restored through a later damages award.
For disputes involving confidential information and restrictive covenants, see Confidential Information, Trade Secrets, and Restrictive Covenant Injunctions.
Is it enough to say that serious harm might occur?
No. The party seeking the injunction must support the alleged irreparable harm with evidence appropriate to the circumstances.
The court is deciding whether intervention is justified before the underlying litigation has been finally determined. The claimed harm should therefore be connected to what is sufficiently likely to occur if relief is refused rather than resting only on general concern, assertion, or speculation.
Depending on the case, the evidentiary record may include affidavit evidence, contracts, financial records, correspondence, corporate documents, evidence concerning confidential information, or other material demonstrating why a remedy available after trial would not adequately address the threatened harm.
Does proving irreparable harm guarantee an injunction?
No. Irreparable harm is only one part of the analysis.
Under the conventional RJR—MacDonald framework, the moving party must also establish a serious question to be tried and satisfy the balance of convenience analysis.
The court considers the three branches together when deciding whether interlocutory relief should be granted.
See What does “balance of convenience” mean in an Ontario injunction motion? for the next stage of the test.
Does the irreparable-harm requirement also apply to a mandatory injunction?
Yes. Where an interlocutory injunction is mandatory in substance, the first-stage merits threshold is more demanding, but the applicant must still establish irreparable harm and satisfy the balance of convenience.
The distinction concerns the first branch of the test: mandatory relief generally requires a strong prima facie case rather than merely a serious question to be tried.
See What is a mandatory injunction in Ontario? for that distinction.
How does ME Law assess irreparable harm?
ME Law examines the specific harm said to require immediate intervention, the evidence supporting that risk, whether the consequences can be quantified, whether damages would provide an adequate remedy, and how closely the threatened harm is connected to the legal rights asserted.
The analysis also considers timing. A potentially serious consequence is not necessarily irreparable if an effective remedy remains available later, while harm that cannot practically be reversed may support a stronger case for interim protection.
Contact ME Law if you are considering seeking an injunction or need to respond to a claim that irreparable harm requires urgent court intervention.