This blog is a complement to one I wrote earlier this his summer about Ontario’s expert problem, “The Credibility Crisis: Rebuilding Trust in Expert Evidence Through Civil Reform”^[1]. In it, I observed that in many mediations (and trials), dueling assessments don’t clarify. They just cancel each other out.

Ontario’s Phase 2 Civil Rules Review^[2] tackles the expert-evidence problem by empowering courts—on a party’s motion or on their own initiative—to order joint litigation experts. More than encouragement, the proposal makes joint experts presumptively required for a defined list of issues that are standardized, math-heavy, or otherwise well-suited to a single neutral:

1. Property valuations of developed land;
2. Business valuations;
3. Past and future economic loss (including competitive-position and earning-capacity loss in personal-injury matters);
4. Care-cost quantification;
5. Life expectancy;
6. Standards of care;
7. Engineering analysis;
8. Fire investigation
9. Handwriting analysis; and
10. Capacity determinations.

For everything else, parties must consider retaining a joint expert first. Only if a joint expert is not suitable may each side retain its own. Unreasonable refusal to consider a joint expert is expressly flagged as a costs factor.

Any dispute about whether a joint expert should be used is to be dealt with at a Directions Conference. The proposal lists suitability factors the court may weigh:

1. Whether the issue falls within the presumptive list;
2. Whether a joint expert will save time or expense;
3. Whether someone has already hired an individual expert;
4. The parties’ ability to pay;
5. Proportionality;
6. Whether individual experts are needed for fairness;
7. The complexity and importance of the issue;
8. Any genuine methodology disagreement and
9. Whether a joint expert could address it by running different scenarios;
10. Whether the trial will be by jury or judge alone; and
11. Any other relevant matter.

If a joint expert is ordered or agreed, the procedures are detailed. The expert is retained by all relevant parties. If they cannot agree on who that is, the court can select from party-prepared lists or set another selection method. Each party may give instructions, but they must simultaneously serve a copy of those instructions on the other instructing parties. No off-channel communications with the expert (or the expert’s affiliates) are permitted—everyone must be present or copied.

If inconsistent instructions can’t be reconciled, the issue goes back to the Directions Conference. The parties must cooperate to provide a complete document brief. If the expert needs more, the expert must say so before completing the report.

The Court can issue Directions on fees and expenses, what documents to produce, inspections or tests to run, and the scope of instructions. Upon request, the Court may  limit the fees and expenses payable. Unless the Court orders otherwise, the instructing parties are jointly and severally liable for the expert’s fees and expenses.

The joint expert must deliver the report, a sworn Attestation of Expert Duty, and a CV to all instructing parties at the same time. After receiving the report, each instructing party may seek clarifications or make submissions on perceived errors, but any such requests must be copied to all. The expert’s responses must also go to all instructing parties.

All parties retain the right to cross-examine the joint expert. When a cross-examination is arranged, the instructing parties are jointly and severally responsible to summons and pay for the expert’s attendance, with those costs treated as assessable disbursements on a costs assessment.

Why Push in This Direction

The status quo, with competing reports that sail past each other, bloats costs and muddies issues. Where the task is chiefly arithmetic or standardized analysis, a single neutral can run the numbers once, disclose the assumptions, and bracket a range. Counsel can then argue which inputs should be preferred.

That is consistent with the Supreme Court’s gatekeeping in White Burgess Langille Inman v. Abbott and Haliburton Co. (2015 SCC 23)^[3], which insists on independence, impartiality, and necessity, and with Moore v. Getahun (2015 ONCA 55)^[4], which permits counsel-expert collaboration so long as the expert’s duty to the Court remains paramount and the process is transparent.

The Upside

A presumptive joint-expert model on the specified issues should compress timelines, reduce duplication, and anchor settlement discussions in a common analytical spine. The Directions Conference provides an early forum to resolve suitability and scope, selection impasses, and methodology disputes. The shared-instructions rule flushes out the usual trench war over what the expert saw and when.

Fee-capping powers and joint/several responsibility create both discipline and certainty around costs.

Clarifications flow on the record, to everyone, at the same time, allowing no private back-channels, no mystery edits. The retained right to cross-examine keeps adversarial testing where it belongs, at the points that actually matter.

Where Caution Is Warranted—Aligned With the Text

The presumptive list includes “standards of care” and “engineering analysis.” Those aren’t always commoditized. The proposal anticipates that reality by directing courts to weigh fairness, complexity, importance, and whether there is a bona fide methodology disagreement that might require alternative scenarios.

In files where the very method or underlying factual predicates are live, such as certain malpractice, product, or complex occupiers’ cases, the safer fit under the proposal’s own factors may be to find that a joint expert is not suitable, permitting each party to retain an expert, while still using the Directions Conference to hard-wire scope, comparators, and timelines. That approach stays squarely within the text, namely joint where suitable, and individual experts where fairness and methodology demand it.

The “Joint” Process Isn’t Immune to Tilt—and How to Guard Against It Under the Rules

A joint retainer can still tilt if one side quietly shapes the inputs. The proposal gives the Court tools to prevent that. It can select the expert if parties deadlock, set or approve the instructions, define the scope of document production, and even limit fees.

Use those levers. Build a single, paginated common brief. Record any late additions before the report is finalized and, where methodologies diverge, require the expert to run both scenarios identified at the Directions Conference.

None of this strays beyond the proposal. It is exactly what its Directions framework is for.

Jury Trials Need Special Care—As the Proposal Recognizes

The proposal expressly tells courts to consider whether the matter is to be tried by a jury or judge alone. In a jury case heavy on credibility and factual disputes, a court-ordered single expert can sound perilously like the court’s witness. That is the kind of proceeding where, applying the listed factors, a court may properly decide that a joint expert is not suitable and that each side should have its own expert, subject to a tight scope and timetable set at the Directions Conference.

Where I Land

I support joint experts on the proposal’s presumptive list when the real work is standardized or mathematical, like developed-land valuations, business valuations, economic loss calculations, care-costing, life expectancy, fire analysis, handwriting, and capacity. You gain speed, cost control, and a common platform for mediation and pretrial.

I oppose forcing a joint expert where the method itself is the battlefield, which the proposal acknowledges by inviting courts to weigh fairness, complexity, importance, and methodological dispute—often with the answer being “run different scenarios” or, if that won’t cure it, permit individual experts. That balance also keeps faith with Westerhof v. Gee Estate 2015 ONCA 206^[5] on the categories of expert evidence, while White Burgess and Moore remain the reliability and process guardrails.

What It Means for Mediation

Expect more mediations informed by a single neutral analysis on the presumptive issues, with clarifications exchanged on the record and no discovery fights about off-channel communications.

Where a joint expert isn’t suitable, the Directions Conference should still narrow the battlefield, by fixing scope, identifying the precise methodological forks, and setting up alternative scenario runs or parallel expert mandates that will actually help the parties price risk.

Bottom Line

The reform gets the center of gravity right, namely using joint experts where the work is standardized and math-driven, and resisting them where fairness and methodology demand adversarial testing. The text gives judges the tools of presumptions, factors, selection powers, shared-instruction rules, document-control, fee limits, and cross-examination rights to keep the process both efficient and fair.

Use joint experts as a door to clarity, not as a duel for one to cancel out the other.