Can a court freeze estate assets while a will challenge is ongoing, before any final decision?

Yes. Where there's a real risk that estate assets could be dissipated, sold, or otherwise put out of reach while a will challenge is still being decided, an Ontario court can grant an interim order restraining the estate trustee or another party from dealing with some or all of the assets until the underlying dispute is resolved, or until the court orders otherwise. This kind of order is meant to preserve the status quo, not to punish anyone or decide who's ultimately entitled to the assets.

Courts don't grant this kind of relief lightly. The party asking for it generally needs to show a genuine, credible risk to the assets — not just that a dispute exists — along with why preserving the assets is necessary and why the harm of not acting could be serious or difficult to undo later. Because an order like this can significantly restrict what an estate trustee is otherwise able to do, including paying legitimate expenses, it's typically tailored carefully, sometimes allowing routine administration to continue while restricting only specific, higher-risk transactions. Anyone concerned about estate assets being put at risk during a will dispute should raise the issue with a lawyer promptly, since this kind of relief is time-sensitive.