
A breakdown of the landmark ruling L.M. v. T.S. and what it means for the enforceability of your Separation Agreement
Legal Analysis: This case commentary was reviewed by Deepa Tailor, Senior Family Lawyer, to explain the binding nature of Secondary Arbitration clauses in Ontario (2026).
Yes. The Ontario Court of Appeal has strongly reinforced that if parents sign a Separation Agreement agreeing to use a specific Arbitrator for future disputes (e.g., changes to the parenting schedule), they must use that process. You cannot bypass the arbitrator and run to family court just because you prefer a judge. If you try, the court will likely 'Stay' (pause) your case and send you back to arbitration.
Understanding the dispute that led to this ruling
The parents had a Separation Agreement with a 'Secondary Arbitration' clause. The mother wanted to move 20km away (changing the school). The agreement said an Arbitrator must decide this.
Instead of calling the Arbitrator, the mother applied directly to the Superior Court, arguing the court always has 'parens patriae' jurisdiction over children.
The Court of Appeal rejected the mother's argument. They ruled that valid arbitration agreements must be respected. The court refused to hear the case, sending it back to the arbitrator.
Deciding the main issues for the first time (e.g., dividing assets, setting the initial custody schedule).
Deciding future changes or implementation issues (e.g., 'The agreement says we share holidays, but we can't agree on Christmas dates'). This case confirms these clauses are ironclad.
Check your Parenting Plan. Does it have a 'Dispute Resolution' clause? If it names an arbitrator or mediator-arbitrator, you cannot file court motions without their permission.
If you ignore the clause and sue in court, your ex can file a 'Motion to Stay.' You will likely lose and be ordered to pay their legal costs.
The court supports arbitration because it is faster and keeps cases out of the backlog. However, you must ensure the arbitration process is fair.
Yes, but only in rare cases where there is immediate danger to a child or the arbitration process is fundamentally unfair/invalid.

Deepa Tailor is the founder of Tailor Law. She closely monitors appellate decisions to ensure her clients' Separation Agreements contain enforceable, durable dispute resolution clauses.
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