What remedies are available if a shareholder breaches a unanimous shareholder agreement in Ontario?

A unanimous shareholder agreement (USA) is a contract, so a breach of it is generally handled through ordinary contract remedies: damages to compensate for the loss the breach caused, and in appropriate cases, specific performance or an injunction to actually enforce a particular term - for example, forcing compliance with a right of first refusal, a shotgun clause, or a restriction on transferring shares to an outsider. Because these agreements often govern control and exit rights that are hard to value in money alone, injunctive relief is sought more often here than in many ordinary commercial disputes.

Many well-drafted shareholder agreements also include their own dispute resolution mechanism - mandatory mediation or arbitration, a valuation process for a forced buyout, or a specific procedure for breach - and courts will generally expect that process to be followed rather than going straight to litigation, unless the agreement doesn't cover the situation or urgent interim relief is needed. A breach of a shareholder agreement can also sometimes overlap with an oppression claim if the same conduct is unfair to you as a shareholder more broadly, so both angles are worth considering together rather than treating them as mutually exclusive.