When Parents Disagree on Medical Decisions for a Child in Ontario

A child needs a vaccination, orthodontic work, or a mental-health referral, and one parent wants to proceed while the other doesn't. If you share decision-making responsibility with your co-parent, this is one of the most common places that disagreement surfaces — and it's worth understanding, before it happens, who actually has the final say.

The answer depends on exactly how your decision-making responsibility is structured, and on whether the situation is an emergency or something that can wait.

Medical Decisions Are a Decision-Making Responsibility Issue

Health care is specifically one of the categories of "significant decisions" that decision-making responsibility covers, alongside education, religion or culture, and significant extracurricular activities. How that authority is allocated between parents — solely to one, shared jointly, or split by category — determines who gets to make a given medical call.

Sole vs. Shared: Who Actually Decides

• Sole decision-making responsibility. If one parent holds sole decision-making responsibility, that parent has the final legal say on medical decisions, full stop — though many separation agreements still expect that parent to consult or inform the other as a matter of good practice, even without a legal obligation to do so.
• Shared (joint) decision-making responsibility. Both parents are expected to discuss and agree on significant medical decisions. Neither parent can unilaterally override the other on a matter within shared responsibility, at least not without going back to the other parent or, if needed, to court.
• Split or domain-specific arrangements. Some parenting plans divide decision-making by subject — for example, one parent has final say on medical decisions specifically, while decisions about school or extracurriculars are handled differently. If your plan does this, the specific wording controls, not a general assumption about who "usually" decides.

Emergency Care vs. Everything Else

This distinction matters more than people expect. "Parenting time" already includes the day-to-day and emergency decisions a parent makes simply because the child is in their care at that moment — regardless of who holds overall decision-making responsibility. That means:

• A parent whose child needs urgent care while in their care can authorize that care without first tracking down the other parent's agreement.
• Non-urgent, significant decisions — elective procedures, ongoing treatment plans, choosing a new specialist — generally fall back to whoever holds decision-making responsibility over health care, and shared responsibility means both parents' agreement is expected.

What to Do When You're Genuinely Stuck

1. Try to resolve it directly first. Put the specific decision, and each parent's position, in writing — email or a co-parenting app works well for creating a clear record.
2. Consider mediation. A neutral third party can often help parents work through a single disputed decision faster, and less expensively, than going to court.
3. Get professional input where it helps. A treating doctor's recommendation, in writing, can sometimes resolve a disagreement about medical necessity without anyone needing a judge's involvement.
4. Ask a lawyer whether an urgent motion is warranted. Where a decision genuinely can't wait and the other parent won't agree, a court can be asked to authorize a specific medical decision — this is generally reserved for situations that are time-sensitive or otherwise can't be resolved through negotiation.
5. Consider whether the decision-making structure itself needs to change. If disputes over medical decisions keep recurring, that pattern is sometimes a reason to revisit the arrangement itself — including through a motion to change an existing order.

Reducing the Risk of This Happening Again

• [ ] Put a process for medical decisions in writing in your parenting plan, not just a general statement that responsibility is "shared"
• [ ] Agree in advance on how routine appointments will be communicated, even where formal agreement isn't required
• [ ] Keep a shared record of the child's medical history, providers, and appointments so both parents are working from the same information
• [ ] Identify, in the plan itself, what counts as "significant" versus routine, so fewer decisions end up in a gray zone

Frequently asked questions