Questions to Ask a Nephrology Expert Witness at Deposition (2026 Guide)

By John Mahoney · Updated 2026-09-01 · 18 questions in 4 concession chains

You are about to cross-examine someone with two decades of training you don't have, on their home turf, about the thing they do every day. That asymmetry is the defining problem of medical-expert depositions — and it gets worse in multi-defendant malpractice cases, where two to four different specialties can be in play in a single case and you have to be conversant in all of them by deposition day.

Nephrology experts testify on acute kidney injury, nephrotoxic-medication cases, and dialysis timing. Kidney function is tracked in routine labs on nearly every hospitalized patient, so these are paper-trail cases — the trend was in the chart, and the questions make the expert own it.

The answer to the asymmetry is not to learn nephrology — it is structure. A concession funnel asks the expert to agree, one fact at a time, to propositions so orthodox that refusing them costs more credibility than granting them. The questions below are a generic-case-safe starting bank, organized into the four chains that structure works through.

How to use these questions

Every question below follows three rules of expert cross-examination: it is leading (it states a fact and asks for agreement), it contains one fact (no compounds — a compound question lets the witness answer the easy half), and it belongs to a concession chain (each answer narrows the room the next answer can live in). Ask them in order. When you get the concession, stop — do not ask the "why" question that lets the expert explain it away.

Chain 1 — Qualifications, retention & scope

Goal: establish on the record that this is a paid, retained witness who never touched the patient, and fix the boundaries of what they actually practice.

Doctor, you were retained by opposing counsel in this case, correct?
You are being compensated for your time reviewing this case and for your testimony today, correct?
You never examined or treated the patient in this case, correct?
Everything you know about this case comes from the materials counsel selected and sent to you, correct?
Kidney function is routinely tracked with standard laboratory values on hospitalized patients, correct?

Chain 2 — Bases-of-opinion lockdown

Goal: freeze the universe. After this chain, any new document, new basis, or new opinion at trial is impeachment material.

You have now told us every document and material you reviewed in forming your opinions, correct?
You are not relying on anything outside that file for the opinions you will give in this case, correct?
You have told us every opinion you intend to offer at trial, correct?
You agree that an opinion you cannot state to a reasonable degree of medical probability is speculation, correct?

Chain 3 — Substantive concessions: the rising creatinine and the medication list

The nephrology funnel is short and brutal because the data is objective and serial. Every question below is orthodox renal medicine.

A rising creatinine signals that kidney function is worsening, correct?
A worsening trend across serial values is more informative than any single value, correct?
Certain commonly used medications are known to be harmful to the kidneys, correct?
When kidney function declines, the medication list should be re-evaluated for those drugs, correct?
Dose adjustments for impaired kidney function are standard practice, correct?
There are recognized indications for starting dialysis, correct?

Chain 4 — Closing the doors

Goal: end with the record sealed. These questions convert silence into a commitment that nothing new is coming at trial.

You are not offering any opinions in this case beyond the ones we have discussed today, correct?
You have not held back any opinion or criticism that you intend to offer at trial, correct?
You are not offering any opinion about the surgical decisions that preceded the kidney injury, correct?

These are the generic questions. Your case isn't generic.

The MedLegal AI Examination Builder generates a complete, case-specific concession-funnel roadmap for deposing a nephrology expert — built from your theory of the case, aware of which side you're on and what kind of witness you're facing, with stop markers, if-they-resist branches, and the doors you should not open. Three free cases, no credit card.

Build my examination → Nephrology depo trainer

Where lawyers get burned deposing nephrology experts

Baseline-creatinine games

What counts as "abnormal" depends on the patient’s baseline, and experts choose the baseline that flatters the defense. Lock the baseline first — which value, from what date, and why — before any question about when the injury became apparent. A shifting baseline is an impeachment gift, but only if you froze it early.

Letting chronic kidney disease absorb the acute injury

The defense narrative is that the kidneys were already failing. Make the expert separate the chronic slope from the acute change on the actual serial values — date by date. A documented step-change sitting on top of a gentle slope is the case, and the expert’s own reading of the numbers proves it.

Letting the ordering/continuing distinction diffuse responsibility

One clinician started the nephrotoxic drug; others continued it as the labs worsened. Experts defend each actor in isolation. Ask about the duty at each renewal point with the then-current labs on the table — continuation with new information is a fresh decision.

FAQ

What questions should I ask a nephrology expert witness at deposition?

Work in four concession chains: (1) qualifications, retention, and scope — establish the expert was retained, is compensated, never treated the patient, and what they do and do not practice; (2) bases-of-opinion lockdown — pin every document reviewed and every opinion they intend to offer; (3) the nephrology-specific substantive chain — well-established propositions such as "A rising creatinine signals that kidney function is worsening"; and (4) closing the doors — confirm on the record that no undisclosed opinions remain. Every question should be leading, contain one fact, and build on the prior answer.

How do I cross-examine a medical expert when I never went to medical school?

You don't out-doctor the doctor — you build concession chains from propositions so well-established that a credible nephrology expert cannot refuse them, then apply those concessions to the facts in the chart. The expert's medical training becomes your asset: the more orthodox the proposition, the more it costs them to fight it. The asymmetry problem is real — especially in multi-defendant cases with two to four specialties — which is why the questions are organized as funnels rather than as debates.

What are the biggest traps when deposing a nephrology expert witness?

The classic traps are letting the expert choose a defense-friendly baseline creatinine after the fact, letting chronic kidney disease absorb what the serial values show as an acute step-change, and letting the distinction between ordering and continuing a nephrotoxic drug diffuse responsibility for it.

Related resources

Examination Builder — a case-specific concession-funnel roadmap from your theory of the case
Nephrology deposition trainer — the other side of the table: how nephrology witnesses are prepped against these questions
All specialties — deposition question guides
Are you a nephrology physician? Join the MedLegal AI expert network

This page is informational only and is not legal advice. Question banks are generic-case-safe starting points — adapt every question to the facts, the jurisdiction, and your theory of the case before using it in a deposition.